Liquid crystal display substrate, method of manufacturing the same, and liquid crystal display device having the same

ABSTRACT

A liquid crystal display substrate capable of providing good reflection display characteristics, a method of manufacturing the same, and a liquid crystal display device having the same are provided. The liquid crystal display substrate contains a plurality of pixel areas each having a reflection area reflecting light incident from a front surface side of the substrate and a transmission area transmitting light incident from a back surface side of the substrate; a wrinkled resin layer formed with a positive light-sensitive resin in the reflection area and having at least a portion thereof a wrinkled surface; a reflection electrode formed with a light reflection material on the wrinkled resin layer and having a wrinkled surface following the surface of the wrinkled resin layer; and light shielding portions formed as an underlayer of the wrinkled resin layer and shielding light incident from the back surface of the substrate.

This is a Divisional of application Ser. No. 10/941,520, filed Sep. 15,2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display substrate, amethod of manufacturing the same, and a liquid crystal display devicehaving the same, and more particularly, it relates to such a substratefor transreflective liquid crystal display that can attain display inboth a transmission mode and a reflection mode, a method ofmanufacturing the same, and a liquid crystal display device having thesame.

2. Description of the Related Art

In recent years, liquid crystal devices are demanded to have higherperformance. According to spread of mobile phones and mobile electronicdevices, in particular, they are strongly demanded to attain lowelectric energy consumption and good usability out of doors. In order toattain low electric energy consumption and good usability out of doors,a reflection liquid crystal display device has been proposed, which hasa pixel electrode having light reflection capability (a reflectionelectrode) and attains display by reflecting outside light to make alight source device unnecessary.

A thin film transistor (TFT) substrate of a reflection liquid crystaldisplay device has a reflection electrode formed thereon with a metallicthin film having high light reflectivity. In the reflection liquidcrystal display device, natural light incident thereon from the displayscreen side or light emitted by utilizing electricity is reflected bythe reflection electrode on the TFT substrate, and the reflected lightis used as a light source for liquid crystal display. The reflectionelectrode has an uneven surface. The uneven surface of the reflectionelectrode can be obtained by previously forming a light-sensitive resinlayer having an uneven surface as an underlayer of the reflectionelectrode. The light incident from the display screen side is diffuselyreflected by the uneven surface of the reflection electrode to obtainhigh luminance and a large viewing angle.

In the reflection liquid crystal display devices disclosed inJP-A-2002-221716 and JP-A-2002-296585, for example, a surface (an upperlayer portion) of an overcoat layer formed with a resin material isapplied to predetermined energy to make the upper layer portion berelatively cured in comparison to a lower layer portion, and then theovercoat layer is subjected to a heat treatment at a temperature equalto or higher than the heat curing point thereof, whereby wrinkledunevenness is formed on the surface of the overcoat layer.

A transreflective liquid crystal display device is also proposed, whichcan attain display in a transmission mode in addition to display in areflection mode as similar to the reflection liquid crystal displaydevice. In the transreflective liquid crystal display device, atransmission area having a transparent electrode formed with a lighttransmission material and a reflection area having a reflectionelectrode formed with a light reflection material are formed on each ofpixel areas. The reflection electrode of the transreflective liquidcrystal display device is formed on a resin layer having an unevensurface, as similar to the reflection liquid crystal display device. Thetransreflective liquid crystal display device referred herein includes aslightly transmission liquid crystal display device, which has anincreased proportion of the reflection area in pixel areas to improvedisplay luminance in a reflection mode, and a slightly reflection liquidcrystal display device, which has an increased proportion of thetransmission area in pixel areas to improve display luminance in atransmission mode.

FIG. 27A is a plan view showing a constitution of a TFT substrate of aconventional transreflective liquid crystal display device. FIG. 27B isa cross sectional view showing the TFT substrate shown in FIG. 27A online X-X. As shown in FIGS. 27A and 27B, a glass substrate 110 of theTFT substrate 102 has a plurality of gate bus lines 112 extending inparallel to each other in the landscape direction in FIG. 27A (providedthat only one of them is shown in FIGS. 27A and 27B).

An insulating film 130 is formed on the gate bus lines 112 on the entiresurface of the substrate (which is sometimes referred to as a gateinsulating film, depending on the position where the film is formed). Aplurality of drain bus lines 114 are formed extending in parallel toeach other in the portrait direction in FIG. 27A as intersecting thegate bus lines 112 with the insulating film 130 intervening therebetween(provided that only two of the drain bus lines 114 are shown in FIG.27A). TFTs 120 are formed in the vicinities of positions where the gatebus lines 112 and the drain bus lines 114 are intersected each other.

The TFT 120 has an active semiconductor layer 128 formed with an a-Silayer on the insulating film 130. A channel protective film 123 isformed on the active semiconductor layer 128. The gate bus line 112 inan area immediately beneath the channel protective film 123 isconfigured to function as a gate electrode of the TFT 120. The channelprotective film 123 has thereon a drain electrode 121 drawn from theadjacent drain bus line 114 and a source electrode 122 disposed to facethe drain electrode 121 through a predetermined gap.

A protective film 132 is formed on the TFT 120 on the entire surface ofthe substrate. A wrinkled resin layer 134 having wrinkled unevenness onthe surface thereof is formed on the protective film 132 in a reflectionarea of each of the pixel areas. A reflection electrode 117 is formed onthe wrinkled resin layer 134. The reflection electrode 117 has awrinkled uneven surface following the surface of the wrinkled resinlayer 134. The reflection electrode 117 and the wrinkled resin layer 134are formed to cover the TFT 120. Separately, a transparent electrode 116is formed on the protective film 132 in a transmission area of each ofthe pixel areas. One pixel is constituted with the reflection area andthe transmission area positioned on the adjacent upper side of thereflection electrode in FIG. 27A. The reflection electrode 117 and thetransparent electrode 116 in the same pixel are electrically connectedto each other. The transparent electrode 116 is electrically connectedthrough a contact hole 124 to a source electrode 122 of a TFT 120 formedas an underlayer of a reflection electrode 117 of a pixel positioned onthe adjacent upper side in FIG. 27A.

A storage capacitor bus line 118 is formed on the glass substrate 110 inparallel to the gate bus line 112 as extending in the landscapedirection in FIG. 27A. The storage capacitor bus line 118 functions asone electrode of a storage capacitor. A storage capacitor electrode 119is formed on the storage capacitor bus line 118 through the insulatingfilm 130. The storage capacitor electrode 119 is electrically connectedto the source electrode 122 and functions as the other electrode of thestorage capacitor. A light leakage preventing film 140 is also formed onthe glass substrate 110 in parallel to the gate bus line 112 and thestorage capacitor bus line 118 in the landscape direction in FIG. 27A.The light leakage preventing film 140 is disposed to shielding thevicinity of the boundary between the reflection area and thetransmission area from light, so as to prevent leakage of light causedby alignment failure of the liquid crystal in the vicinity of theboundary between the areas.

The wrinkled resin layer 134 in the TFT substrate 120 shown in FIGS. 27Aand 27B is formed by the following procedures. A positivelight-sensitive resin is coated on a whole surface of a glass substratehaving TFTs and the like formed thereon to form a resin layer. The glasssubstrate is placed on an exposing stage in an exposing apparatus, andthe resin layer is exposed through a photomask that shields areas to bereflection areas from light. By this, the resin layer is exposed onareas other than the reflection areas. Subsequently, the resin layer isdeveloped to remove the resin layer in the exposed area by dissolving ina developer solution, whereby the resin layer in the non-exposedreflection areas remains as not dissolved in the developer solution. Thesurface of the remaining resin layer is irradiated with UV light to curethe upper layer portion of the resin layer. Subsequently, the resinlayer is subjected to a heat treatment at a temperature equal to orhigher than the heat curing point thereof, so as to form a wrinkledresin layer having wrinkled unevenness on the surface thereof.

In the step of exposing the resin layer, however, the light reflected bythe surface of the exposing stage is also incident on the resin layer inthe reflection areas. Accordingly, the resin layer in the reflectionareas is exposed and cured to such an extent that it is not dissolved inthe developer solution. In general, the surface of the exposing stagehas grooves formed thereon. Therefore, the intensity of the lightincident on the resin layer in the reflection areas varies depending onthe presence and absence of the grooves on the surface of the exposingstage, and thus, the extent of curing of the resin layer variesdepending on the positions of the grooves. Accordingly, uniform wrinkledunevenness cannot be formed on the surface of the resin layer in thesubsequent step to fluctuate the shape of wrinkled unevennesscorresponding to the positions of the grooves on the surface of theexposing stage. Consequently, a transreflective liquid crystal displaydevice thus manufactured has such a problem that display ununiformitycorresponding to the positions of the grooves on the surface of theexposing stage is viewed upon display in a reflection mode, so as tofail to obtain an intended reflectivity and good reflection uniformity.

SUMMARY OF THE INVENTION

An object of the invention is to provide a liquid crystal displaysubstrate capable of providing good reflection display characteristics,a method of manufacturing the same, and a liquid crystal display devicehaving the same.

The aforementioned object of the invention can be attained by a liquidcrystal display substrate containing: a plurality of pixel areas eachhaving at least a portion thereof a reflection area reflecting lightincident from a front surface side of the substrate; a wrinkled resinlayer formed with a positive light-sensitive resin in the reflectionarea, the wrinkled resin layer having at least a portion thereof awrinkled surface; a reflection electrode formed with a light reflectionmaterial on the wrinkled resin layer, the reflection electrode having awrinkled surface following the surface of the wrinkled resin layer; anda light shielding portion formed as an underlayer of the wrinkled resinlayer, the light shielding portion shielding light incident from a backsurface of the substrate.

According to the invention, such a liquid crystal display device can berealized that provides good reflection display characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a constitution of a liquid crystaldisplay device according to a first embodiment of the invention;

FIG. 2 is a schematic diagram showing an equivalent circuit of a liquidcrystal display substrate according to the first embodiment of theinvention;

FIGS. 3A and 3B are a plan view and a cross sectional view showing aconstitution of a liquid crystal display substrate according to thefirst embodiment of the invention;

FIGS. 4A and 4B are a plan view and a cross sectional view showing aconstitution of a liquid crystal display substrate according to amodified example of the first embodiment of the invention;

FIGS. 5A and 5B are a plan view and a cross sectional view showing aconstitution of a liquid crystal display substrate according to a secondembodiment of the invention;

FIGS. 6A and 6B are a plan view and a cross sectional view showing aconstitution of a liquid crystal display substrate according to amodified example of the second embodiment of the invention;

FIGS. 7A and 7B are a plan view and a cross sectional view showing aconstitution of a liquid crystal display substrate according to a thirdembodiment of the invention;

FIGS. 8A and 8B are a plan view and a cross sectional view showing aconstitution of a liquid crystal display substrate according to a fourthembodiment of the invention;

FIGS. 9A and 9B are a plan view and a cross sectional view showing aconstitution of a liquid crystal display substrate according to amodified example of the fourth embodiment of the invention;

FIG. 10 is a cross sectional view showing a constitution of a liquidcrystal display substrate according to a fifth embodiment of theinvention;

FIGS. 11A and 11B are cross sectional views showing a method ofmanufacturing a liquid crystal display substrate according to the fifthembodiment of the invention;

FIGS. 12A and 12B are cross sectional views showing a method ofmanufacturing a liquid crystal display substrate according to the fifthembodiment of the invention;

FIG. 13 is a cross sectional view showing a constitution of a liquidcrystal display substrate according to a sixth embodiment of theinvention;

FIGS. 14A and 14B are cross sectional views showing a method ofmanufacturing a liquid crystal display substrate according to the sixthembodiment of the invention;

FIGS. 15A and 15B are cross sectional views showing a method ofmanufacturing a liquid crystal display substrate according to the sixthembodiment of the invention;

FIG. 16 is a cross sectional view showing a constitution of a liquidcrystal display substrate according to a seventh embodiment of theinvention;

FIGS. 17A to 17C are cross sectional views showing a method ofmanufacturing a liquid crystal display substrate according to theseventh embodiment of the invention;

FIG. 18 is a cross sectional view showing a constitution of a liquidcrystal display substrate according to an eighth embodiment of theinvention;

FIGS. 19A and 19B are cross sectional views showing a method ofmanufacturing a liquid crystal display substrate according to the eighthembodiment of the invention;

FIGS. 20A and 20B are cross sectional views showing a method ofmanufacturing a liquid crystal display substrate according to the eighthembodiment of the invention;

FIG. 21 is a cross sectional view showing a constitution of a liquidcrystal display substrate according to a ninth embodiment of theinvention;

FIGS. 22A and 22B are cross sectional views showing a method ofmanufacturing a liquid crystal display substrate according to the ninthembodiment of the invention;

FIGS. 23A and 23B are cross sectional views showing a method ofmanufacturing a liquid crystal display substrate according to the ninthembodiment of the invention;

FIG. 24 is a cross sectional view showing a constitution of a liquidcrystal display substrate according to a tenth embodiment of theinvention;

FIGS. 25A and 25B are cross sectional views showing a method ofmanufacturing a liquid crystal display substrate according to the tenthembodiment of the invention;

FIGS. 26A and 26B are cross sectional views showing a method ofmanufacturing a liquid crystal display substrate according to the tenthembodiment of the invention; and

FIGS. 27A and 27B are a plan view and a cross sectional view showing aconstitution of a TFT substrate of a conventional transreflective liquidcrystal display device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

A liquid crystal display substrate according to a first embodiment ofthe invention and a liquid crystal display device using the same will bedescribed with reference to FIGS. 1 to 4B. FIG. 1 is a schematic diagramshowing a constitution of a transreflective liquid crystal displaydevice according to a first embodiment of the invention. As shown inFIG. 1, the transreflective liquid crystal display device has such astructure that a transparent electrode formed with a light transmissionmaterial, a reflection electrode formed with a light reflection materialand a TFT substrate 2 having a TFT and the like formed in each of pixelareas are attached to an opposite substrate 4 having a common electrode,a CF layer and the like as facing each other, and a liquid crystal issealed between them.

The TFT substrate 2 has a gate bus line driving circuit 80 having adriver IC mounted thereon for driving the plurality of gate bus linesand a drain bus line driving circuit 82 having a driver IC mountedthereon for driving the plurality of drain bus lines. The drivingcircuits 80 and 82 output a scanning signal and a data signal to thepredetermined gate bus line or drain bus line based on the predeterminedsignal output from a control circuit 84.

The opposite substrate 4 has a CF layer having one color selected fromred (R), green (G) and blue (B) formed for each pixel areas. The facingsurfaces of the substrates 2 and 4 have alignment films for aligning theliquid crystal molecules to a predetermined direction. The TFT substrate2 has, on the surface opposite to that having an element formed, apolarizing plate 87 attached thereto. A backlight unit 88 is disposed onthe side of the polarizing plate 87 opposite to the TFT substrate 2. Onthe contrary, a polarizing plate 86 is attached to the surface of theopposite substrate 4 opposite to that having the CF layer formed.

FIG. 2 is a schematic diagram showing an equivalent circuit of theelement formed on the TFT substrate 2. FIG. 3A is a plan view showingthe constitution of approximately one pixel area of the TFT substrate 2,and FIG. 3B is a cross sectional view showing the constitution of theTFT substrate 2 on line A-A in FIG. 3A. As shown in FIGS. 2, 3A and 3B,a glass substrate 10 of the TFT substrate 2 has the plurality of gatebus lines 12 extending in parallel to each other in the landscapedirection in FIGS. 2 and 3A (provided that only one of them is shown inFIG. 3A).

An insulating film (gate insulating film) 30 is formed on the gate buslines 12 on the entire surface of the substrate. The plurality of drainbus lines 14 are formed extending in parallel to each other in theportrait direction in FIGS. 2 and 3A as intersecting the gate bus lines12 with the insulating film 30 intervening therebetween (provided thatonly two of the drain bus lines 14 are shown in FIG. 3A). A channelprotective film type TFTs 20, for example, are formed in the vicinitiesof positions where the gate bus lines 12 and the drain bus lines 14 areintersected each other.

The TFT 20 has an active semiconductor layer 28 formed with an a-Silayer on the insulating film 30. A channel protective film 23 is formedon the active semiconductor layer 28. On the channel protective film 23,a drain electrode 21 withdrawn from the adjacent drain bus line 14 andan n⁺a-Si layer 51 as an under ohmic contact layer thereof, and a sourceelectrode 22 and a lower n⁺a-Si layer 51 as an underlayer thereof areformed to face each other through a predetermined gap. The drainelectrode 21 and the source electrode 22 each has, for example, anaccumulated layer structure having a titanium (Ti) layer 21 a, analuminum (Al) layer 21 b and a Ti layer (21 c). In this constitution,the gate bus line 12 immediately beneath the channel protective film 23functions as a gate electrode of the TFT 20.

A protective film 32 is formed on the TFT 20 on the entire surface ofthe substrate. A wrinkled resin layer 34 having wrinkled unevenness onthe surface thereof is formed on the protective film 32 in a reflectionarea of each of the pixel areas. The wrinkled resin layer 34 is formedby using a positive light-sensitive resin. A reflection electrode 17 isformed on the wrinkled resin layer 34. The reflection electrode 17 isformed with an electroconductive film having light reflection capabilityand has, for example, a structure having a Ti layer 17 a and an Al layer17 b accumulated in this order. The reflection electrode 17 has awrinkled uneven surface following the surface of the wrinkled resinlayer 34. Light incident from the display screen side is diffuselyreflected by the wrinkled surface of the reflection electrode 17 toobtain good reflection display characteristics. The reflectionelectrodes 17 formed on each of the pixels are disposed to cover the TFT20 which drives the pixel adjacent lower side of the pixel in FIG. 3A.

Separately, a transparent electrode 16 is formed on the protective film32 in a transmission area of each of the pixel areas. The transparentelectrode 16 is formed with an electroconductive film having lighttransmissibility, such as ITO (indium tin oxide). One pixel isconstituted with the reflection area and the transmission areapositioned on the adjacent upper side of the reflection electrode inFIG. 3A. The reflection electrode 17 and the transparent electrode 16 inthe same pixel are electrically connected to each other.

A storage capacitor bus line 18 is formed in parallel to the gate busline 12 as extending in the landscape direction in FIGS. 2 and 3A. Thestorage capacitor bus line 18 is formed with the same material as thegate bus line 12. A storage capacitor electrode 19 is formed on thestorage capacitor bus line 18 for each of the pixels through theinsulating film 30. The storage capacitor electrode 19 is formed withthe same material as the drain bus line 14. A light leakage preventingfilm 40 is also formed in parallel to the gate bus line 12 in thelandscape direction in FIG. 3A. The light leakage preventing film 40 isdisposed to shield the vicinity of the boundary between the reflectionarea and the transmission area from light, so as to prevent leakage oflight caused by alignment failure of the liquid crystal in the vicinityof the boundary between the areas. The light leakage preventing film 40is formed with the same material as the gate bus line 12 and the storagecapacitor bus line 18, and is, for example, in an electrically floatingstate.

The TFT substrate 2 of this embodiment has, as an underlayer of thewrinkled resin layer 34 formed in the reflection area, light shieldingportions 60 a and 60 b for shielding light incident from the backsurface side of the glass substrate 10 (the lower side in FIG. 3B). Thelight shielding portions 60 a and 60 b are formed with the same materialas the gate bus line 12, the storage capacitor bus line 18 and the lightleakage preventing film 40 simultaneously therewith. The light shieldingportion 60 a is disposed between the light leakage preventing film 40and the gate bus line 12. The light shielding portion 60 a iselectrically connected to the light leakage preventing film 40 and iselectrically separated from the gate bus line 12. The light shieldingportion 60 b is disposed between the gate bus line 12 and the storagecapacitor bus line 18. The light shielding portion 60 b is electricallyseparated from the gate bus line 12 and is electrically connected to thestorage capacitor bus line 18. A large proportion of the reflection area(i.e., the area having the wrinkled resin layer 34 formed) is shieldedfrom light incident from the back surface side of the glass substrate 10by the gate bus line 12, the storage capacitor bus line 18, the lightleakage preventing film 40 and the light shielding portions 60 a and 60b (with portions of the drain electrode 21 and the source electrode 22).In the area having the wrinkled resin layer 34 formed, the proportion ofthe area shielded from light incident from the back surface side of theglass substrate 10 is preferably higher, for example, 30% or more.

The TFT 20, the bus lines 12, 14 and 18, the light leakage preventingfilm 40 and the light shielding portions 60 a and 60 b are formed by thephotolithography process through a series of steps of semiconductorprocess, i.e., forming of a film, coating of a resist, exposure,development, etching, and removal of resist.

According to this embodiment, in the step of patterning a positivelight-sensitive resin layer for forming the wrinkled resin layer 34 inthe reflection area, reflected light on the exposing stage in theexposing apparatus is shielded by the light shielding portions 60 a and60 b, and thus the light is substantially not incident on thelight-sensitive resin layer in the reflection area. Therefore, a heattreatment by applying energy to the surface thereof in the subsequentstep provides such a wrinkled resin layer 34 that has uniform wrinkledunevenness formed thereon. Consequently, the reflection electrode 17formed on the wrinkled resin layer 34 also has uniform wrinkledunevenness to obtain a desired inclined plane distribution with goodcontrollability. According to this embodiment, therefore, excellentreflection uniformity and stable reflectivity can be obtained to realizea transreflective liquid crystal display device having good reflectiondisplay characteristics. Furthermore, since the light shielding portions60 a and 60 b are formed in the same process step as the gate bus line12, the storage capacitor bus line 18 and the light leakage preventingfilm 40, no process step is added to the manufacturing method of the TFTsubstrate 2.

A modified example of the constitution of the liquid crystal displaysubstrate of this embodiment will be described with reference to FIGS.4A and 4B. FIG. 4A is a plan view showing the constitution of thevicinity of the reflection area of one pixel area of the TFT substrate 2according to this modified example, and FIG. 4B is a cross sectionalview showing the constitution of the TFT substrate 2 on line B-B in FIG.4A. In this modified example, as shown in FIGS. 4A and 4B, the lightshielding portions 60 a and 60 b each is divided into plural portions,and is electrically separated from the light leakage preventing film 40and the storage capacitor bus line 18, as different from theconstitution shown in FIGS. 3A and 3B. The modified example is the sameas the constitution shown in FIGS. 3A and 3B in such a standpoint thatthe light shielding portions 60 a and 60 b are formed with the samematerial as the gate bus line 12 and the like.

The three portions of the light shielding portion 60 a formed betweenthe gate bus line 12 and the light leakage preventing film 40 areelectrically separated from both the gate bus line 12 and the lightleakage preventing film 40 and thus is in a floating state. The twoportions of the light shielding portion 60 b formed between the gate busline 12 and the storage capacitor bus line 18 are electrically separatedfrom both the gate bus line 12 and the light leakage preventing film 40and thus is in a floating state. In this modified example, even in thecase where the light shielding portion 60 a is shorted to one of thegate bus line 12 and the light leakage preventing film 40 due tocontamination with electroconductive foreign matters or the like, thegate bus line 12 and the light leakage preventing film 40 are notshorted to each other. Similarly, even in the case where the lightshielding portion 60 b is shorted to one of the gate bus line 12 and thestorage capacitor bus line 18, the gate bus line 12 and the storagecapacitor bus line 18 are not shorted to each other. According to thismodified example, therefore, the manufacturing yield of the TFTsubstrate 2 can be further improved, in addition to the similar effectas in the constitution shown in FIGS. 3A and 3B.

Second Embodiment

A liquid crystal display substrate according to a second embodiment ofthe invention will be described with reference to FIGS. 5A to 6B. FIG.5A is a plan view showing the constitution of the vicinity of thereflection area of one pixel area of the TFT substrate 2 according tothis embodiment, and FIG. 5B is a cross sectional view showing theconstitution of the TFT substrate 2 on line C-C in FIG. 5A. As shown inFIGS. 5A and 5B, the TFT substrate 2 according to this embodiment has,as an underlayer of the wrinkled resin layer 34 formed in the reflectionarea, light shielding portions 61 a and 61 b for shielding lightincident from the back surface side of the glass substrate 10 (the lowerside in FIG. 5B). The light shielding portions 61 a and 61 b are formedwith the same material as the drain bus line 14, the drain electrode 21,the source electrode 22 and the storage capacitor electrode 19simultaneously therewith. The light shielding portion 61 a iselectrically connected to the drain bus line 14 and the drain electrode21 and is disposed between the light leakage preventing film 40 and thegate bus line 12. The light shielding portion 61 b is electricallyconnected to the source electrode 22 and the storage capacitor electrode19 and is disposed between the gate bus line 12 and the storagecapacitor bus line 18. A large proportion of the reflection area (i.e.,the area having the wrinkled resin layer 34 formed) is shielded fromlight incident from the back surface side of the glass substrate 10 bythe gate bus line 12, the storage capacitor bus line 18, the lightleakage preventing film 40 and the light shielding portions 61 a and 61b.

According to this embodiment, in the step of patterning a positivelight-sensitive resin layer for forming the wrinkled resin layer 34 inthe reflection area, reflected light on the exposing stage in theexposing apparatus is shielded by the light shielding portions 61 a and61 b, and thus the light is substantially not incident on thelight-sensitive resin layer in the reflection area, as similar to thefirst embodiment. Therefore, a heat treatment by applying energy to thesurface thereof in the subsequent step provides such a wrinkled resinlayer 34 that has uniform wrinkled unevenness formed thereon.Consequently, the reflection electrode 17 formed on the wrinkled resinlayer 34 also has uniform wrinkled unevenness to obtain a desiredinclined plane distribution with good controllability. According to thisembodiment, therefore, excellent reflection uniformity and stablereflectivity can be obtained to realize a transreflective liquid crystaldisplay device having good reflection display characteristics.Furthermore, since the light shielding portions 61 a and 61 b are formedin the same process step as the drain bus line 14, the drain electrode21, the source electrode 22 and the storage capacitor electrode 19, noprocess step is added to the manufacturing method of the TFT substrate2.

A modified example of the constitution of the liquid crystal displaysubstrate of this embodiment will be described with reference to FIGS.6A and 6B. FIG. 6A is a plan view showing the constitution of thevicinity of the reflection area of one pixel area of the TFT substrate 2according to this modified example, and FIG. 6B is a cross sectionalview showing the constitution of the TFT substrate 2 on line D-D in FIG.6A. In this modified example, as shown in FIGS. 6A and 6B, the lightshielding portions 61 a and 61 b each is divided into plural portions,and is electrically separated from the drain bus line 14, the drainelectrode 21, the source electrode 22 and the storage capacitorelectrode 19, as different from the constitution shown in FIGS. 5A and5B. The modified example is the same as the constitution shown in FIGS.5A and 5B in such a standpoint that the light shielding portions 61 aand 61 b are formed with the same material as the drain bus line 14 andthe like.

The three portions of the light shielding portion 61 a formed betweenthe gate bus line 12 and the light leakage preventing film 40 areelectrically separated from both the drain bus line 14 and the drainelectrode 21 and thus is in a floating state. The two portions of thelight shielding portion 61 b formed between the gate bus line 12 and thestorage capacitor bus line 18 are electrically separated from all thedrain bus line 14, the source electrode 22 and the storage capacitorelectrode 19 and thus is in a floating state. In this modified example,even in the case where the light shielding portion 61 a is shorted toone of the two drain bus lines 14 adjacent to each other in thelandscape direction of the pixel due to contamination withelectroconductive foreign matters or the like, the two drain bus lines14 are not shorted to each other. Similarly, even in the case where thelight shielding portion 61 b is shorted to one of the drain bus line 14and the source electrode 22 (or the storage capacitor electrode 19), thedrain bus line 14 and the source electrode 22 are not shorted to eachother. According to this modified example, therefore, the manufacturingyield of the TFT substrate 2 can be further improved, in addition to thesimilar effect as in the constitution shown in FIGS. 5A and 5B.

Third Embodiment

A liquid crystal display substrate according to a third embodiment ofthe invention will be described with reference to FIGS. 7A to 7B. FIG.7A is a plan view showing the constitution of the vicinity of thereflection area of one pixel area of the TFT substrate 2 according tothis embodiment, and FIG. 7B is a cross sectional view showing theconstitution of the TFT substrate 2 on line E-E in FIG. 7A. As shown inFIGS. 7A and 7B, the TFT substrate 2 according to this embodiment has,as an underlayer of the wrinkled resin layer 34 formed in the reflectionarea, light shielding portions 60 a, 60 b, 61 a and 61 b for shieldinglight incident from the back surface side of the glass substrate 10 (thelower side in FIG. 7B). The light shielding portions 60 a and 60 b areformed with the same material as the gate bus line 12, the storagecapacitor bus line 18 and the light leakage preventing film 40simultaneously therewith. The light shielding portion 60 a is disposedbetween the gate bus line 12 and the light leakage preventing film 40and is electrically separated from both the gate bus line 12 and thelight leakage preventing film 40. The light shielding portion 60 b isdisposed between the gate bus line 12 and the storage capacitor bus line18 and is electrically separated from both the gate bus line 12 and thestorage capacitor bus line 18.

At the position corresponding to the gap between the light leakagepreventing film 40 and the light shielding portion 60 a, the lightshielding portion 61 a is disposed through the insulating film 30 tooverlap partly the light leakage preventing film 40 and the lightshielding portion 60 a. Similarly, at the position corresponding to thegap between the gate bus line 12 and the light shielding portion 60 a,the light shielding portion 61 a is disposed through the insulating film30 to overlap partly the gate bus line 12 and the light shieldingportion 60 a. Furthermore, at the position corresponding to the gapbetween the gate bus line 12 and the light shielding portion 60 b, thelight shielding portion 61 b is disposed through the insulating film 30to overlap partly the gate bus line 12 and the light shielding portion60 b. The light shielding portions 61 a and 61 b are formed with thesame material as the drain bus line 14, the drain electrode 21, thesource electrode 22 and the storage capacitor electrode 19simultaneously therewith. As described herein, in this embodiment, thelight shielding portions are formed with different materials dependingon the areas where the light shielding portions are formed. Thesubstantially whole reflection area is shielded from light incident fromthe back surface side of the glass substrate 10 by the gate bus line 12,the storage capacitor bus line 18, the light leakage preventing film 40,the drain electrode 21, the source electrode 22, the storage capacitorelectrode 19 and the light shielding portions 60 a, 60 b, 61 a and 61 b.

According to this embodiment, in the step of patterning a positivelight-sensitive resin layer for forming the wrinkled resin layer 34 inthe reflection area, reflected light on the exposing stage is shieldedby the light shielding portions 60 a, 60 b, 61 a and 61 b, and thus thelight is substantially not incident on the light-sensitive resin layerin the reflection area, as similar to the first and second embodiments.Therefore, a heat treatment by applying energy to the surface thereof inthe subsequent step provides such a wrinkled resin layer 34 that hasuniform wrinkled unevenness formed thereon. Consequently, the reflectionelectrode 17 formed on the wrinkled resin layer 34 also has uniformwrinkled unevenness to obtain a desired inclined plane distribution withgood controllability. According to this embodiment, therefore, excellentreflection uniformity and stable reflectivity can be obtained to realizea transreflective liquid crystal display device having good reflectiondisplay characteristics. Furthermore, since the light shielding portions60 a and 60 b are formed in the same process step as the gate bus line12, the storage capacitor bus line 18 and the light leakage preventingfilm 40, and the light shielding portions 61 a and 61 b are formed inthe same process steps as the drain bus line 14, the drain electrode 21,the source electrode 22 and the storage capacitor electrode 19, noprocess step is added to the manufacturing method of the TFT substrate2.

Fourth Embodiment

A liquid crystal display substrate according to a fourth embodiment ofthe invention will be described with reference to FIGS. 8A to 9B. FIG.8A is a plan view showing the constitution of the vicinity of thereflection area of one pixel area of the TFT substrate 2 according tothis embodiment, and FIG. 8B is a cross sectional view showing theconstitution of the TFT substrate 2 on line F-F in FIG. 8A. As shown inFIGS. 8A and 8B, the TFT substrate 2 according to this embodiment has,as an underlayer of the wrinkled resin layer 34 formed in the reflectionarea, light shielding portions 62 a and 62 b for shielding lightincident from the back surface side of the glass substrate 10 (the lowerside in FIG. 8B). The TFT substrate 2 has a channel etching type TFT 25,which is different from the channel protective film type TFT 20 in thefirst to third embodiments.

The TFT 25 has an active semiconductor layer 28 formed with an a-Silayer on an insulating film 30. On the active semiconductor layer 28, adrain electrode 21 withdrawn from the adjacent drain bus line 14 and ann⁺a-Si layer 51 as an underlayer thereof, and a source electrode 22 anda lower n⁺a-Si layer 51 as an underlayer thereof are formed to face eachother through a predetermined gap. For example, the source electrode 22has a stick-like planar shape. The drain electrode 21 is disposed tosurround the source electrode 22 in a C-shape. The channel area surfaceof the active semiconductor layer 28 is partly etched for ensuringseparation and insulation between the drain electrode 21 and the sourceelectrode 22. The active semiconductor layer 28 has a thickness, forexample, of from 150 to 200 nm upon formation thereof, and the thicknessof the active semiconductor layer 28 at the portion having a surfacebeing etched is, for example, about 100 nm. The gate bus line 12immediately beneath the active semiconductor layer 28 functions as agate electrode of the TFT 25. The gate bus line 12 in this embodimenthas a larger width in the area functioning as the gate electrode thanthat of the other areas.

The light shielding portions 62 a and 62 b are formed with the samematerial as the active semiconductor layer 28 of the TFT 25simultaneously therewith. The light shielding portions 62 a and 62 bhave a thickness of about 100 nm, which is substantially the same as thethickness of the active semiconductor layer 28 of the TFT 25 in the areahaving a surface being etched, and has a function of shielding(absorbing) light. As described herein, this embodiment utilizes such aconstitution that the active semiconductor layer 28 of the channeletching type TFT 25 is formed to have a larger thickness than the activesemiconductor layer 28 of the channel protective film type TFT 20 (forexample, about from 30 to 50 nm). The light shielding portion 62 a isdisposed between the gate bus line 12 and the light leakage preventingfilm 40 and is electrically separated from the active semiconductorlayer 28, the drain electrode 21, the drain bus line 14, the gate busline 12 and the light leakage preventing film 40. The light shieldingportion 62 b is disposed between the gate bus line 12 and the storagecapacitor bus line 18 and is electrically separated from the activesemiconductor layer 28, the source electrode 22, the storage capacitorelectrode 19, the gate bus line 12 and the storage capacitor bus line18. A large proportion of the reflection area is shielded from lightincident from the back surface side of the glass substrate 10 by thegate bus line 12, the storage capacitor bus line 18, the light leakagepreventing film 40 and the light shielding portions 62 a and 62 b.

According to this embodiment, in the step of patterning a positivelight-sensitive resin layer for forming the wrinkled resin layer 34 inthe reflection area, reflected light on the exposing stage is shieldedby the light shielding portions 62 a and 62 b, and thus the light issubstantially not incident on the light-sensitive resin layer in thereflection area, as similar to the first to third embodiments.Therefore, a heat treatment by applying energy to the surface thereof inthe subsequent step provides such a wrinkled resin layer 34 that hasuniform wrinkled unevenness formed thereon. Consequently, the reflectionelectrode 17 formed on the wrinkled resin layer 34 also has uniformwrinkled unevenness to obtain a desired inclined plane distribution withgood controllability. According to this embodiment, therefore, excellentreflection uniformity and stable reflectivity can be obtained to realizea transreflective liquid crystal display device having good reflectiondisplay characteristics. Furthermore, since the light shielding portions62 a and 62 b are formed in the same process step as the activesemiconductor layer 28, no process step is added to the manufacturingmethod of the TFT substrate 2.

A modified example of the constitution of the liquid crystal displaysubstrate of this embodiment will be described with reference to FIGS.9A and 9B. FIG. 9A is a plan view showing the constitution of thevicinity of the reflection area of one pixel area of the TFT substrate 2according to this modified example, and FIG. 9B is a cross sectionalview showing the constitution of the TFT substrate 2 on line G-G in FIG.9A. In this modified example, as shown in FIGS. 9A and 9B, the lightshielding portion 62 a partly overlaps the light leakage preventing film40. At the gap between the two adjacent light shielding portions 62 a(i.e., on the surrounding of the light shielding portion 62 a), a lightshielding portion 60 a extending from the light leakage preventing film40 is disposed, which is formed with the same material as the gate busline 12 simultaneously therewith. At the gap between the light shieldingportion 62 a and the drain electrode 21, a light shielding portion 60 a′is disposed, which is formed with the same material as the lightshielding portion 60 a simultaneously therewith. Separately, a lightshielding portion 60 b, which is formed with the same material as thegate bus line 12 simultaneously therewith, is disposed on thesurrounding of the light shielding portion 62 b. The light shieldingportion 60 b is electrically separated from both the gate bus line 12and the storage capacitor bus line 18. As described herein, in thismodified embodiment, the light shielding portions are formed withdifferent materials depending on the areas where the light shieldingportions are formed. The substantially whole reflection area is shieldedfrom light incident from the back surface side of the glass substrate 10by the gate bus line 12, the storage capacitor bus line 18, the lightleakage preventing film 40, the drain electrode 21, the source electrode22, the storage capacitor electrode 19 and the light shielding portions60 a, 60 a′, 60 b, 62 a and 62 b. According to this modified example,therefore, further uniform wrinkled unevenness can be formed on thereflection electrode 17 in comparison to the constitution shown in FIGS.8A and 8B, so as to provide better reflection display characteristics.

Fifth Embodiment

A liquid crystal display substrate according to a fifth embodiment ofthe invention and a manufacturing method thereof will be described withreference to FIGS. 10 to 12B. FIG. 10 is a cross sectional view showinga constitution of a TFT substrate 2 according to this embodiment. InFIG. 10, the area having a TFT 20 of a pixel formed therein is shown onthe left side, a transmission area of the pixel is shown at the center,and a reflection area of the adjacent pixel is shown on the right side.As shown in FIG. 10, the TFT substrate 2 of this embodiment has aninsulating film 31 as an underlayer of a gate electrode (gate bus line)12 of the channel protective film type TFT 20. A transparent electrode16 is formed immediately above the glass substrate 10 in thetransmission area. The surface of the transparent electrode 16 isexposed through an opening 27 where the protective film 32 and theinsulating films 30 and 31 are removed. The transparent electrode 16 iselectrically connected to the source electrode 22 of the TFT 20 throughthe reflection electrode 17. A light shielding portion 63 is formed asan underlayer of the insulating film 31 in the reflection area. Thelight shielding portion 63 has such a constitution that an ITO layer 52formed with the same material as the transparent electrode 16 and a highmelting point metal layer 53 having a light shielding capability areaccumulated in this order and patterned into the same shape.

A manufacturing method of the liquid crystal display substrate accordingto this embodiment will be described. FIGS. 11A to 12B are crosssectional views showing the manufacturing method of the TFT substrate 2according to this embodiment. As shown in FIG. 11A, an ITO layer 52having a thickness, for example, of 70 nm and a high melting point metallayer 53 having a thickness, for example, of 100 nm are formed bysputtering directly on a glass substrate 10 as a transparent insulatingsubstrate or after forming a protective film, such as SiO_(x), thereondepending on necessity. By this, an electroconductive film having athickness of about 170 nm having the ITO layer 52 and the high meltingpoint metal layer 53 accumulated is formed on the whole surface of thesubstrate. Examples of the material for forming the high melting pointmetal layer 53 include Ti, chromium (Cr), molybdenum (Mo), tantalum(Ta), tungsten (W) and alloys thereof. A resist is then coated on thewhole surface of the electroconductive film and patterned by using afirst photomask (or a reticle) to form a resist pattern having apredetermined shape. Subsequently, wet etching by using, for example, amixed reagent of acetic acid, nitric acid and phosphoric acid, and wetetching using, for example, a reagent, such as oxalic acid, are effectedby using the resist pattern as an etching mask. Consequently, a lightshielding portion 63 is formed on at least a portion of an area to be areflection area, and an electroconductive film (electroconductive layer)54 having a predetermined shape is formed on an area to be atransmission area.

As shown in FIG. 11B, by the plasma CVD process a silicon nitride film(SiN film) having a thickness, for example, of 200 nm is formed on thelight shielding portion 63 and the electroconductive film 54 on thewhole surface of the substrate to form an insulating film 31.

As shown in FIG. 12A, an Al layer (or an Al alloy layer) 55 having athickness, for example, of 130 nm and a high melting point metal layer(such as a Ti layer or a Ti alloy layer) 56 having a thickness, forexample, of 70 nm are formed in this order by sputtering on theinsulating layer 31 on the whole surface of the substrate. Consequently,an electroconductive film having a thickness of 200 nm containing the Allayer 55 and the high melting point metal layer 56 accumulated isformed. Examples of the Al alloy include those materials that areobtained by adding one or plurality of neodymium (Nd), silicon (Si),copper (Cu), Ti, W, Ta and scandium (Sc) to Al. Examples of the highmelting point metal include Cr, Mo, Ta, W and alloys thereof. A resistis then coated on the whole surface of the electroconductive film andpatterned by using a second photomask to form a resist pattern having apredetermined shape. Subsequently, dry etching using, for example, achlorine series gas is effected by using the resist pattern as anetching mask. Consequently, a gate bus line 12, a storage capacitor busline 18 (not shown in the figure) and a gate bus line terminal (notshown in the figure) are formed.

An SiN film having a thickness, for example, of 400 nm is formed by theplasma CVD process on the gate bus line 12, the storage capacitor busline 18 and the gate bus line terminal on the whole surface of thesubstrate, so as to form an insulating film (gate insulating film) 30.An a-Si layer having a thickness, for example, of 30 nm is then formedby the plasma CVD process on the whole surface of the insulating layer30. Subsequently, an SiN film having a thickness, for example, of 150 nmis formed by the plasma CVD process on the whole surface of the a-Silayer. A resist is coated by spin coating on the whole surface of theSiN film to form a resist layer. The glass substrate 10 is then exposedfrom the back surface side thereof by using the gate bus line 12 as amask. Subsequently, the glass substrate 10 is exposed from the frontsurface side thereof by using a third photomask. The resist layer isthen developed, and the resist layer in the exposed area is removed bydissolution. Consequently, a resist pattern is formed in a self aligningmanner only on the area for forming the channel protective film on thegate bus line 12. Dry etching using a fluorine series gas is theneffected by using the resist pattern as an etching mask to form achannel protective film 23.

Immediately after cleaning the surface of the a-Si layer (removal of aspontaneous oxidized film) by using diluted hydrofluoric acid, an n⁺a-Silayer having a thickness, for example, of 30 nm is formed on the wholesurface of the substrate by the plasma process. A high melting pointmetal layer (such as a Ti layer or a Ti alloy layer) 57 having athickness, for example, of 40 nm, an Al layer (or an Al alloy layer) 58having a thickness, for example, of 75 nm and a high melting point metallayer (such as a Ti layer or a Ti alloy layer) 59 having a thickness,for example, of 80 nm are then formed by sputtering in this order toform an electroconductive film. Examples of the high melting point metalinclude Cr, Mo, Ta, W and alloys thereof. It is necessary that the highmelting point metal layer 59 is not removed but remains upon removing byetching the high melting point metal layer 53 in the transmission areain the subsequent process step, and therefore, the materials for formingthe high melting point metal layers 53 and 59 are selected underconsideration of etching selectivity thereof (see FIG. 12B).

A resist is then coated on the whole surface of the electroconductivefilm and patterned by using a fourth photomask to form a resist patternhaving a predetermined shape. The electroconductive film, the n⁺a-Silayer and the a-Si layer are subjected to dry etching using a chlorineseries gas by using the resist pattern as an etching mask. Consequently,a drain electrode 21 and a source electrode 22 of the TFT 20, an activesemiconductor layer 28, a storage capacitor electrode 19 (not shown inthe figure), a drain bus line 14 (not shown in the figure) and a drainbus line terminal (not shown in the figure) are formed. The channelprotective film 23 functions as an etching stopper upon etching, and thea-Si layer as an underlayer thereof is not etched but remains. Accordingto the aforementioned operations, a channel protective film type TFT 20is formed.

As shown in FIG. 12B, an SiN film having a thickness, for example, of300 nm is formed by the plasma CVD process on the whole surface of thesubstrate to form a protective film 32. A resist is then coated on thewhole surface of the protective film 32 and patterned by using a fifthphotomask to form a resist pattern having a predetermined shape. Theprotective film 32 (and the insulating films 30 and 31) is subjected todry etching using a mixed gas of a fluorine series gas and an O₂ gas byusing the resist pattern as an etching mask. Consequently, a contacthole 26 on the source electrode 22, a contact hole (not shown in thefigure) on the storage capacitor electrode 19 and a contact hole (notshown in the figure) on the gate bus line terminal and the drain busline terminal are formed. Simultaneously, the protective film 32 and theinsulating films 30 and 31 on the electroconductive film 54 in thetransmission area are removed to form an opening 27. Subsequently, wetetching using a mixed reagent of acetic acid, nitric acid and phosphoricacid is effected. Consequently, the high melting point metal layer 53 asan upper layer of the electroconductive film 54 exposed through theopening 27 is removed, and the ITO layer 52 as a lower layer thereofremains, so as to form a transparent electrode 16.

A positive light-sensitive novolak resin, for example, is coated on thewhole surface of the substrate by using a spin coater or a slit coaterto form a light-sensitive resin layer having a thickness, for example,of about from 0.5 to 4 μm. Subsequently, the substrate is subjected to aheat treatment at a temperature of 160° C. or lower. The light-sensitiveresin layer is then exposed by using a sixth photomask and is developedby using an alkali developer solution, such as TMAH (tetramethylammoniumhydroxide), so as to form an overcoat (OC) layer (resin layer) having apredetermined shape. The OC layer is formed on at least a portion of thearea to be the reflection area. In the exposing step for patterning,since the light shielding portion 63 is formed as an underlayer (i.e.,on the side of the glass substrate 10) of the light-sensitive resinlayer, light reflected on the exposing stage of the exposing apparatusis substantially not incident on the light-sensitive resin layer in thereflection area.

The OC layer is then annealed at a temperature of from 100 to 180° C.for from 0.2 to 60 minutes by using a clean oven or a hot plate. Thesurface of the OC layer is then irradiated with UV light having awavelength of from 200 to 470 nm at an energy density of from 10 to 550mJ/cm² for from 5 to 300 seconds. The OC layer is then annealed by usinga clean oven or the like at a temperature equal to or higher than theheat curing point thereof (from 180 to 230° C.) for about 1 hour.Consequently, a wrinkled resin layer 34 having wrinkled unevenness onthe surface thereof is formed in the reflection area (see FIG. 10). Asdescribed in the foregoing, in this embodiment, light reflected by theexposing stage of the exposing apparatus is substantially not incidenton the light-sensitive resin in the reflection area, and therefore, awrinkled resin layer 34 having uniform wrinkled unevenness can beobtained through the subsequent UV light irradiation and heat treatment.

In the constitution shown in FIGS. 3A and 3B, for example, there is sucha possibility that reflected light from the exposing stage is incidentthrough the gap between the light shielding portions 60 a and 60 b andthe gate bus line 12. Therefore, there is such a possibility that thewrinkled unevenness is deformed in a partial area of the wrinkled resinlayer 34 depending on the positions of the grooves on the surface of theexposing stage and that display unevenness depending on the areaproportion of the gap to the reflection area is formed. In order toprevent the phenomenon, the glass substrate 10 may be subjected toexposure from the back surface side (i.e., the lower side in the figure)under predetermined exposing conditions after patterning the OC layerand before subjecting to the heat treatment at a temperature equal to orhigher than the heat curing point. Consequently, the OC layer in thearea corresponding to the gap between the light shielding portions 60 aand 60 b and the gate bus line 12 is substantially uniformly cured overall the pixels, whereby display unevenness is not viewed although nowrinkled unevenness is formed in that area through the subsequent heattreatment.

A Ti layer (or a Ti alloy layer) 17 a having a thickness, for example,of 100 nm and an Al layer (or an Al alloy layer) 17 b having athickness, for example, of 100 nm are formed by sputtering on the wholesurface of the wrinkled resin layer 34. A high melting point metal layerformed with Cr, Mo, Ta, W or alloys thereof may be formed instead of theTi layer. A resist is then coated on the whole surface of the Al layer17 b and patterned by using a seventh photomask to form a resist patternhaving a predetermined shape. Subsequently, dry etching using a chlorineseries gas is effected by using the resist pattern as an etching mask.Consequently, a reflection electrode 17 is formed in the reflection areaincluding the wrinkled resin layer 34. The surface of the reflectionelectrode 17 has a wrinkled uneven surface according to the surface ofthe wrinkled resin layer 34. The reflection electrode 17 is electricallyconnected to the source electrode 22 through the contact hole 26, and iselectrically connected to the storage capacitor electrode 19 through acontact hole not shown in the figure. The reflection electrode 17 isalso electrically connected to the transparent electrode 16 through aportion of the opening 27. Thereafter, the substrate is subjected to aheat treatment at a temperature of from 150 to 230° C., preferably 200°C. According to the aforementioned process steps, the TFT substrate 2shown in FIG. 10 is completed.

According to this embodiment, in the step of patterning the positivelight-sensitive resin layer for forming the wrinkled resin layer 34 inthe reflection area, light reflected from the exposing stage is shieldedby the light shielding portion 63 and the like, and thus the light issubstantially not incident on the light-sensitive resin layer in thereflection area, as similar to the first to fourth embodiments.Therefore, a heat treatment by applying energy to the surface thereof inthe subsequent step provides such a wrinkled resin layer 34 that hassubstantially uniform wrinkled unevenness formed thereon. Consequently,the reflection electrode 17 formed on the wrinkled resin layer 34 alsohas substantially uniform wrinkled unevenness to obtain a desiredinclined plane distribution with good controllability. According to thisembodiment, therefore, excellent reflection uniformity and stablereflectivity can be obtained to realize a transreflective liquid crystaldisplay device having good reflection display characteristics.

Furthermore, since the light shielding portion 63 is patterned by usingthe same photomask (the first photomask) as the transparent electrode16, and the high melting point metal layer 53 on the transparentelectrode 16 is removed by using the predetermined etchant afterexposing through the opening 27 formed simultaneously with the contacthole 26. In this embodiment, therefore, the light shielding portion 63is formed by using no additional photomask, and thus no process step isadded to the manufacturing method of the TFT substrate 2.

Sixth Embodiment

A liquid crystal display substrate according to a sixth embodiment ofthe invention and a manufacturing method thereof will be described withreference to FIGS. 13 to 15B. FIG. 13 is a cross sectional view showinga constitution of a TFT substrate 2 according to this embodiment. InFIG. 13, the area having a TFT 20 of a pixel formed therein is shown onthe left side, a transmission area of the pixel is shown at the center,and a reflection area of the adjacent pixel is shown on the right side,as similar to FIGS. 10 to 12B. As shown in FIG. 13, the TFT substrate 2of this embodiment has the same constitution as the fifth embodimentexcept that it has a channel etching type TFT 25. That is, the TFTsubstrate 2 has a light shielding portion 63 formed by accumulating anITO layer 52 formed with the same material as a transparent electrode 16and a high melting point metal layer 53 having light shieldingcapability in this order, which are then patterned in the same shape.

A manufacturing method of the liquid crystal display substrate accordingto this embodiment will be described. FIGS. 14A to 15B are crosssectional views showing the manufacturing method of the TFT substrate 2according to this embodiment. As shown in FIG. 14A, an ITO layer 52having a thickness, for example, of 70 nm and a high melting point metallayer 53 having a thickness, for example, of 100 nm are formed bysputtering directly on a glass substrate 10 as a transparent insulatingsubstrate or after forming a protective film, such as SiO_(x), thereondepending on necessity. Consequently, an electroconductive film having athickness of about 170 nm having the ITO layer 52 and the high meltingpoint metal layer 53 accumulated is formed on the whole surface of thesubstrate. A resist is then coated on the whole surface of theelectroconductive film and patterned by using a first photomask to forma resist pattern having a predetermined shape. Subsequently, wet etchingby using, for example, a mixed reagent of acetic acid, nitric acid andphosphoric acid, and wet etching using, for example, a reagent, such asoxalic acid, are effected by using the resist pattern as an etchingmask. Consequently, a light shielding portion 63 is formed on at least aportion of an area to be a reflection area, and an electroconductivefilm 54 is formed on an area to be a transmission area.

As shown in FIG. 14B, by the plasma process, an SiN film having athickness, for example, of 200 nm is formed on the light shieldingportion 63 and the electroconductive film 54 on the whole surface of thesubstrate to form an insulating film 31.

As shown in FIG. 15A, an Al layer (or an Al alloy layer) 55 having athickness, for example, of 130 nm and a high melting point metal layer(such as a Ti layer or a Ti alloy layer) 56 having a thickness, forexample, of 70 nm are formed in this order by sputtering on theinsulating layer 31 on the whole surface of the substrate. Consequently,an electroconductive film having a thickness of 200 nm containing the Allayer 55 and the high melting point metal layer 56 accumulated isformed. A resist is then coated on the whole surface of theelectroconductive film and patterned by using a second photomask to forma resist pattern having a predetermined shape. Subsequently, dry etchingusing, for example, a chlorine series gas is effected by using theresist pattern as an etching mask. Consequently, a gate bus line 12, astorage capacitor bus line 18 (not shown in the figure) and a gate busline terminal (not shown in the figure) are formed.

An SiN film having a thickness, for example, of 400 nm is formed by theplasma CVD process on the gate bus line 12, the storage capacitor busline 18 and the gate bus line terminal on the whole surface of thesubstrate, so as to form an insulating film (gate insulating film) 30.An a-Si layer having a thickness, for example, of 150 nm is then formedby the plasma CVD process on the whole surface of the insulating layer30. Subsequently, an n⁺a-Si layer having a thickness, for example, of 30nm is formed by the plasma CVD process on the whole surface of the a-Silayer.

A resist is coated by spin coating on the whole surface of the n⁺a-Silayer to form a resist layer. The glass substrate 10 is then exposedfrom the front surface side thereof by using a third photomask. Theresist layer is then developed, and the resist layer in the exposed areais removed by dissolution. Consequently, a resist pattern is formed onthe area for forming a TFT 25. Dry etching using a fluorine series gasis then effected by using the resist pattern as an etching mask.Consequently, an active semiconductor layer 28 and the n⁺a-Si layer 51as an upper layer thereof are formed in an island shape.

A high melting point metal layer (such as a Ti layer or a Ti alloylayer) 57 having a thickness, for example, of 40 nm, an Al layer (or anAl alloy layer) 58 having a thickness, for example, of 75 nm and a highmelting point metal layer (such as a Ti layer or a Ti alloy layer) 59having a thickness, for example, of 80 nm are formed by sputtering inthis order to form an electroconductive film. Examples of the highmelting point metal include Cr, Mo, Ta, W and alloys thereof. It isnecessary that the high melting point metal layer 59 is not removed butremains upon removing by etching the high melting point metal layer 53in the transmission area in the subsequent process step, and therefore,the materials for forming the high melting point metal layers 53 and 59are selected under consideration of etching selectivity thereof (seeFIG. 15B).

A resist is then coated on the whole surface of the electroconductivefilm and patterned by using a fourth photomask to form a resist patternhaving a predetermined shape. The electroconductive film and the n⁺a-Silayer 51 are subjected to dry etching using a chlorine series gas byusing the resist pattern as an etching mask. In order to separatecertainly the drain electrode 21 and the n⁺a-Si layer 51 as an underlayer thereof from the source electrode 22 and the n⁺a-Si layer 51 as anunder layer thereof, the etching is effected up to the surface of theactive semiconductor layer 28 (channel etching). Consequently, the drainelectrode 21 and the source electrode 22 of the TFT 25, a storagecapacitor electrode 19 (not shown in the figure), a drain bus line 14(not shown in the figure) and a drain bus line terminal (not shown inthe figure) are formed. According to the aforementioned operations, achannel etching type TFT 25 is formed.

As shown in FIG. 15B, an SiN film having a thickness, for example, of300 nm is formed by the plasma CVD process on the whole surface of thesubstrate to form a protective film 32. A resist is then coated on thewhole surface of the protective film 32 and patterned by using a fifthphotomask to form a resist pattern having a predetermined shape. Theprotective film 32 (and the insulating films 30 and 31) is subjected todry etching using a mixed gas of a fluorine series gas and an O₂ gas byusing the resist pattern as an etching mask. Consequently, a contacthole 26 on the source electrode 22, a contact hole (not shown in thefigure) on the storage capacitor electrode 19 and a contact hole (notshown in the figure) on the gate bus line terminal and the drain busline terminal are formed. Simultaneously, the protective film 32 and theinsulating films 30 and 31 on the electroconductive film 54 in thetransmission area are removed to form an opening 27. Subsequently, wetetching using a mixed reagent of acetic acid, nitric acid and phosphoricacid is effected. Consequently, the high melting point metal layer 53 asan upper layer of the electroconductive film 54 exposed through theopening 27 is removed, and the ITO layer 52 as a lower layer thereofremains, so as to form a transparent electrode 16.

A positive light-sensitive novolak resin, for example, is coated on thewhole surface of the substrate by using a spin coater or a slit coaterto form a light-sensitive resin layer having a thickness, for example,of about from 0.5 to 4 μm. Subsequently, the substrate is subjected to aheat treatment at a temperature of 160° C. or lower. The light-sensitiveresin layer is then exposed by using a sixth photomask and is developedby using an alkali developer solution, such as TMAH, so as to form an OClayer having a predetermined shape. The OC layer is formed on at least aportion of the area to be the reflection area. In the exposing step forpatterning, since the light shielding portion 63 is formed as anunderlayer (i.e., on the side of the glass substrate 10) of thelight-sensitive resin layer, light reflected on the exposing stage ofthe exposing apparatus is substantially not incident on thelight-sensitive resin layer in the reflection area.

The OC layer is then annealed at a temperature of from 100 to 180° C.for from 0.2 to 60 minutes by using a clean oven or a hot plate. Thesurface of the OC layer is then irradiated with UV light having awavelength of from 200 to 470 nm at an energy density of from 10 to 550mJ/cm² for from 5 to 300 seconds. Subsequently, depending on necessity,the glass substrate 10 is exposed from the back surface side thereof.The OC layer is then annealed by using a clean oven or the like at atemperature of from 180 to 230° C. for about 1 hour. Consequently, awrinkled resin layer 34 having wrinkled unevenness on the surfacethereof is formed in the reflection area (see FIG. 13). As described inthe foregoing, in this embodiment, light reflected by the exposing stageof the exposing apparatus is substantially not incident on thelight-sensitive resin layer in the reflection area, and therefore, awrinkled resin layer 34 having uniform wrinkled unevenness can beobtained through the subsequent UV light irradiation and heat treatment.

A Ti layer (or a Ti alloy layer) 17 a having a thickness, for example,of 100 nm and an Al layer (or an Al alloy layer) 17 b having athickness, for example, of 100 nm are formed by sputtering on the wholesurface of the wrinkled resin layer 34. A resist is then coated on thewhole surface of the Al layer 17 b and patterned by using a seventhphotomask to form a resist pattern having a predetermined shape.Subsequently, dry etching using a chlorine series gas is effected byusing the resist pattern as an etching mask. Consequently, a reflectionelectrode 17 is formed in the reflection area including the wrinkledresin layer 34. The surface of the reflection electrode 17 has awrinkled uneven surface according to the surface of the wrinkled resinlayer 34. The reflection electrode 17 is electrically connected to thesource electrode 22 through the contact hole 26, and is electricallyconnected to the storage capacitor electrode 19 through a contact holenot shown in the figure. The reflection electrode 17 is alsoelectrically connected to the transparent electrode 16 through a portionof the opening 27. Thereafter, the substrate is subjected to a heattreatment at a temperature of from 150 to 230° C., preferably 200° C.According to the aforementioned process steps, the TFT substrate 2 shownin FIG. 13 is completed.

According to this embodiment, in the step of patterning the positivelight-sensitive resin layer for forming the wrinkled resin layer 34 inthe reflection area, light reflected from the exposing stage is shieldedby the light shielding portion 63 and the like, and thus the light issubstantially not incident on the light-sensitive resin layer in thereflection area, as similar to the first to fifth embodiments.Therefore, a heat treatment by applying energy to the surface thereof inthe subsequent step provides such a wrinkled resin layer 34 that hasuniform wrinkled unevenness formed thereon. Consequently, the reflectionelectrode 17 formed on the wrinkled resin layer 34 also hassubstantially uniform wrinkled unevenness to obtain a desired inclinedplane distribution with good controllability. According to thisembodiment, therefore, excellent reflection uniformity and stablereflectivity can be obtained to realize a transreflective liquid crystaldisplay device having good reflection display characteristics.

Furthermore, since the light shielding portion 63 is patterned by usingthe same photomask (the first photomask) as the transparent electrode16, and the high melting point metal layer 53 on the transparentelectrode 16 is removed by using the predetermined etchant afterexposing through the opening 27 formed simultaneously with the contacthole 26. In this embodiment, therefore, the light shielding portion 63is formed by using no additional photomask, and thus no process step isadded to the manufacturing method of the TFT substrate 2.

Seventh Embodiment

A liquid crystal display substrate according to a seventh embodiment ofthe invention and a manufacturing method thereof will be described withreference to FIGS. 16 to 17C. FIG. 16 is a cross sectional view showinga constitution of a TFT substrate 2 according to this embodiment. InFIG. 16, the area having a TFT 20 of a pixel formed therein is shown onthe left side, a transmission area of the pixel is shown at the center,and a reflection area of the adjacent pixel is shown on the right side,as similar to FIGS. 10 to 15B. As shown in FIG. 16, the TFT substrate 2of this embodiment has, in the transmission area, a transparentelectrode 16 formed directly on the glass substrate 10. The surface ofthe transparent electrode 16 is exposed through an opening 27 where aprotective film 32 and an insulating film 30 are removed. Thetransparent electrode 16 is electrically connected to the sourceelectrode 22 of the TFT 20 through the reflection electrode 17. A gatebus line (gate electrode) 12 has such a constitution that an ITO layer52 formed with the same material as the transparent electrode 16, a highmelting point metal layer 70, an Al layer 71 and a high melting pointmetal layer 72 are accumulated in this order. A light shielding portion64 is formed as an underlayer of the insulating film 30 in thereflection area. The light shielding portion 64 has such a constitutionthat an ITO layer 52 formed with the same material as the transparentelectrode 16, a high melting point metal layer 70, an Al layer 71 and ahigh melting point metal layer 72 are accumulated in this order, assimilar to the gate bus line 12. The layers constituting the lightshielding portion 64 are patterned into the same shape.

A manufacturing method of the liquid crystal display substrate accordingto this embodiment will be described. FIGS. 17A to 17C are crosssectional views showing the manufacturing method of the TFT substrate 2according to this embodiment. As shown in FIG. 17A, an ITO layer 52, ahigh melting point metal layer 70, an Al layer 71 and a high meltingpoint metal layer 72 are formed in this order to form anelectroconductive film directly on a glass substrate 10 or after forminga protective film, such as SiO_(x), thereon depending on necessity. Aresist is then coated on the whole surface of the electroconductive filmand patterned by using a first photomask to form a resist pattern havinga predetermined shape. Subsequently, wet etching by using, for example,a mixed reagent of acetic acid, nitric acid and phosphoric acid, and wetetching using, for example, a reagent, such as oxalic acid, are effectedby using the resist pattern as an etching mask. Consequently, agate busline 12, a storage capacitor bus line 18 (not shown in the figure) and agate bus line terminal (not shown in the figure) are formed, a lightshielding portion 64 is formed on at least a portion of an area to be areflection area, and an electroconductive film 54 is formed on an areato be a transmission area.

As shown in FIG. 17B, an SiN film is formed by the plasma CVD process onthe gate bus line 12, the light shielding portion 64 and theelectroconductive film 54 on the whole surface of the substrate to forman insulating film 30. An a-Si layer is then formed by the plasma CVDprocess on the while surface of the insulating layer 30. Subsequently,an SiN film is formed by the plasma CVD process on the whole surface ofthe a-Si layer. A resist is then coated by spin coating or the like onthe whole surface of the SiN film to form a resist layer. The glasssubstrate 10 is then exposed from the back surface side thereof by usingthe gate bus line 12 as a mask. Subsequently, the glass substrate 10 isexposed from the front surface side thereof by using a second photomask.The resist layer is then developed, and the resist layer in the exposedarea is removed by dissolution. Consequently, a resist pattern is formedin a self aligning manner only on the area for forming the channelprotective film on the gate bus line 12. Dry etching using a fluorineseries gas is then effected by using the resist pattern as an etchingmask to form a channel protective film 23.

Immediately after cleaning the surface of the a-Si layer by usingdiluted hydrofluoric acid, an n⁺a-Si layer is formed by the plasma CVDprocess on the whole surface of the substrate. A high melting pointmetal layer (such as a Ti layer or a Ti alloy layer) 57, an Al layer (oran Al alloy layer) 58 and a high melting point metal layer (such as a Tilayer or a Ti alloy layer) 59 are then formed by sputtering in thisorder to form an electroconductive film.

A resist is then coated on the whole surface of the electroconductivefilm and patterned by using a third photomask to form a resist patternhaving a predetermined shape. The electroconductive film, the n⁺a-Silayer and the a-Si layer are subjected to dry etching using a chlorineseries gas by using the resist pattern as an etching mask. Consequently,a drain electrode 21 and a source electrode 22 of the TFT 20, an activesemiconductor layer 28, a storage capacitor electrode 19 (not shown inthe figure), a drain bus line 14 (not shown in the figure) and a drainbus line terminal (not shown in the figure) are formed. The channelprotective film 23 functions as an etching stopper upon etching, and thea-Si layer as an underlayer thereof is not etched but remains. Accordingto the aforementioned operations, a channel protective film type TFT 20is formed.

As shown in FIG. 17C, an SiN film is formed by the plasma CVD process onthe whole surface of the substrate to form a protective film 32. Aresist is then coated on the whole surface of the protective film 32 andpatterned by using a fourth photomask to form a resist pattern having apredetermined shape. The protective film 32 (and the insulating film 30)is subjected to dry etching using a mixed gas of a fluorine series gasand an O₂ gas by using the resist pattern as an etching mask.Consequently, a contact hole 26 on the source electrode 22, a contacthole (not shown in the figure) on the storage capacitor electrode 19 anda contact hole (not shown in the figure) on the gate bus line terminaland the drain bus line terminal are formed. Simultaneously, theprotective film 32 and the insulating film 30 on the electroconductivefilm 54 in the transmission area are removed to form an opening 27.

A positive light-sensitive novolak resin, for example, is coated on thewhole surface of the substrate by using a spin coater or a slit coaterto form a light-sensitive resin layer having a thickness, for example,of about from 0.5 to 4 μm. Subsequently, the substrate is subjected to aheat treatment at a temperature of 160° C. or lower. The light-sensitiveresin layer is then exposed by using a fifth photomask and is developedby using an alkali developer solution, such as TMAH, so as to form an OClayer having a predetermined shape. The OC layer is formed on at least aportion of the area to be the reflection area. In the exposing step forpatterning, since the light shielding portion 64 is formed as anunderlayer (i.e., on the side of the glass substrate 10) of thelight-sensitive resin layer, light reflected on the exposing stage ofthe exposing apparatus is substantially not incident on thelight-sensitive resin layer in the reflection area.

The OC layer is then annealed at a temperature of from 100 to 180° C.for from 0.2 to 60 minutes by using a clean oven or a hot plate. Thesurface of the OC layer is then irradiated with UV light having awavelength of from 200 to 470 nm at an energy density of from 10 to 550mJ/cm² for from 5 to 300 seconds. Subsequently, depending on necessity,the glass substrate 10 is exposed from the back surface side thereof.The OC layer is then annealed by using a clean oven or the like at atemperature of from 180 to 230° C. for about 1 hour. Consequently, awrinkled resin layer 34 having wrinkled unevenness on the surfacethereof is formed in the reflection area (see FIG. 16). As described inthe foregoing, in this embodiment, light reflected by the exposing stageof the exposing apparatus is substantially not incident on thelight-sensitive resin in the reflection area, and therefore, a wrinkledresin layer 34 having uniform wrinkled unevenness can be obtainedthrough the subsequent UV light irradiation and heat treatment.

A Ti layer (or a Ti alloy layer) 17 a and an Al layer (or an Al alloylayer) 17 b are formed by sputtering on the whole surface of thewrinkled resin layer 34. A resist is then coated on the whole surface ofthe Al layer 17 b and patterned by using a sixth photomask to form aresist pattern having a predetermined shape. Subsequently, dry etchingusing a chlorine series gas is effected by using the resist pattern asan etching mask. Consequently, a reflection electrode 17 is formed inthe reflection area including the wrinkled resin layer 34. The surfaceof the reflection electrode 17 on the wrinkled resin layer 34 has awrinkled uneven surface following the surface of the wrinkled resinlayer 34. The reflection electrode 17 is electrically connected to thesource electrode 22 through the contact hole 26, and is electricallyconnected to the storage capacitor electrode 19 through a contact holenot shown in the figure. The reflection electrode 17 is alsoelectrically connected to the transparent electrode 16. By the etchingoperation, the high melting point metal layer 72, the Al layer 71 andthe high melting point metal layer 70 of the electroconductive film 54exposed through the opening 27 are removed, and the ITO layer 52 as thelowermost layer remains, so as to form a transparent electrode 16.Thereafter, the substrate is subjected to a heat treatment at atemperature of from 150 to 230° C., preferably 200° C. According to theaforementioned process steps, the TFT substrate 2 shown in FIG. 16 iscompleted.

According to this embodiment, in the step of patterning the positivelight-sensitive resin layer for forming the wrinkled resin layer 34 inthe reflection area, light reflected from the exposing stage is shieldedby the light shielding portion 64 and the like, and thus the light issubstantially not incident on the light-sensitive resin layer in thereflection area, as similar to the first to sixth embodiments.Therefore, a heat treatment by applying energy to the surface thereof inthe subsequent step provides such a wrinkled resin layer 34 that hassubstantially uniform wrinkled unevenness formed thereon. Consequently,the reflection electrode 17 formed on the wrinkled resin layer 34 alsohas substantially uniform wrinkled unevenness to obtain a desiredinclined plane distribution with good controllability. According to thisembodiment, therefore, excellent reflection uniformity and stablereflectivity can be obtained to realize a transreflective liquid crystaldisplay device having good reflection display characteristics.

Furthermore, since the light shielding portion 64 is patterned by usingthe same photomask (the first photomask) as the transparent electrode16, as similar to the fifth and sixth embodiments. The high meltingpoint metal layer 70, the Al layer 71 and the high melting point metallayer 72 on the transparent electrode 16 are removed through the etchingstep for forming the reflection electrode 17 after exposing through theopening 27 formed simultaneously with the contact hole 26. In thisembodiment, therefore, the light shielding portion 64 is formed by usingno additional photomask, and thus no process step is added to themanufacturing method of the TFT substrate 2.

In this embodiment, furthermore, the transparent electrode 16 and thelight shielding portion 64 are patterned by using the same photomask asthe gate bus line 12 and the like. Therefore, the number of photomaskscan be reduced by one in comparison to the fifth and sixth embodiments.

While this embodiment exemplifies the TFT substrate 2 having the channelprotective film type TFT 20, the invention can also be applied to a TFTsubstrate 2 having a channel etching type TFT 25.

Eighth Embodiment

A liquid crystal display substrate according to an eighth embodiment ofthe invention and a manufacturing method thereof will be described withreference to FIGS. 18 to 20B. FIG. 18 is a cross sectional view showinga constitution of a TFT substrate 2 according to this embodiment. InFIG. 18, the area having a TFT 20 of a pixel formed therein is shown onthe left side, a transmission area of the pixel is shown at the centerand a reflection area of the adjacent pixel is shown on the right side,as similar to FIGS. 10 to 17C. As shown in FIG. 18, the TFT substrate 2of this embodiment has, on an insulating film 30 in the transmissionarea, an a-Si layer 75, which is formed with the same material with anactive semiconductor layer 28 of the TFT 20 integrally therewith. Atransparent electrode 16 is formed on the a-Si layer 75. In thereflection area, a light shielding portion 65 is formed on theinsulating film 30 but as an underlayer of a protective film 32. Thelight shielding portion 65 has such a constitution that an a-Si layer 73formed with the same material as the active semiconductor layer 28, anITO layer 52 formed with the same material as the transparent electrode16 and a high melting point metal layer 74 are accumulated in thisorder. The layers constituting the light shielding portion 65 arepatterned into the same shape. In this embodiment, while the a-Si layer75 is formed as an underlayer of the transparent electrode 16 in thetransmission area, the thickness of the active semiconductor layer 28 ofthe channel protective film type TFT 20 and the thickness of the a-Silayer 75 are about from 30 to 50 nm, and thus the light transmittance inthe transmission area is substantially not decreased.

A manufacturing method of the liquid crystal display substrate accordingto this embodiment will be described. FIGS. 19A to 20B are crosssectional views showing the manufacturing method of the TFT substrate 2according to this embodiment. As shown in FIG. 19A, an Al layer (or anAl alloy layer) 55 and a high melting point metal layer (an Mo layer) 56are formed in this order by sputtering directly on a glass substrate 10or after forming a protective film, such as SiO_(x), thereon dependingon necessity. Consequently, an electroconductive film containing the Allayer 55 and the high melting point metal layer 56 is formed. Additionalexamples of the high melting point metal include Cr, Ti, Ta, W andalloys thereof. A resist is then coated on the whole surface of theelectroconductive film and patterned by using a first photomask to forma resist pattern having a predetermined shape. Subsequently, dry etchingusing, for example a chlorine series gas is effected by using the resistpattern as an etching mask. Consequently, a gate bus line 12, a storagecapacitor bus line 18 (not shown in the figure) and a gate bus lineterminal (not shown in the figure) are formed.

As shown in FIG. 19B, an SiN film is formed by the plasma CVD process onthe gate bus line 12, the storage capacitor bus line 18 and the gate busline terminal on the whole surface of the substrate to form aninsulating film 30. An a-Si layer 76 is then formed by the plasma CVDprocess on the while surface of the insulating layer 30. Subsequently,an SiN film is formed by the plasma CVD process on the whole surface ofthe a-Si layer 76. A resist is then coated by spin coating or the likeon the whole surface of the SiN film to form a resist layer. The glasssubstrate 10 is then exposed from the back surface side thereof by usingthe gate bus line 12 as a mask. Subsequently, the glass substrate 10 isexposed from the front surface side thereof by using a second photomask.The resist layer is then developed, and the resist layer in the exposedarea is removed by dissolution. Consequently, a resist pattern is formedin a self aligning manner only on the area for forming the channelprotective film on the gate bus line 12. Dry etching using a fluorineseries gas is then effected by using the resist pattern as an etchingmask to form a channel protective film 23.

An ITO layer 52 and a high melting point metal layer 74 are formed inthis order by sputtering on the whole surface of the channel protectivefilm 23. Consequently, an electroconductive film having the ITO layer 52and the high melting point metal layer 74 accumulated is formed on thewhole surface of the substrate. A resist is then coated on the wholesurface of the electroconductive film and patterned by using a thirdphotomask to form a resist pattern having a predetermined shape.Subsequently, wet etching by using, for example, a mixed reagent ofacetic acid, nitric acid and phosphoric acid, and wet etching using, forexample, a reagent, such as oxalic acid, are effected by using theresist pattern as an etching mask. Consequently, a light shieldingportion 65′ is formed on at least a portion of an area to be areflection area, and an electroconductive film 54 is formed in thetransmission area.

As shown in FIG. 20A, immediately after cleaning the surface of the a-Silayer 76 by using diluted hydrofluoric acid, an n⁺a-Si layer is formedby the plasma CVD process on the whole surface of the substrate. A highmelting point metal layer (such as a Ti layer or a Ti alloy layer) 57,an Al layer (or an Al alloy layer) 58 and a high melting point metallayer 59 are then formed by sputtering in this order to form anelectroconductive film.

A resist is then coated on the whole surface of the electroconductivefilm and patterned by using a fourth photomask to form a resist patternhaving a predetermined shape. The electroconductive film, the n⁺a-Silayer and the a-Si layer 76 are subjected to dry etching using achlorine series gas by using the resist pattern as an etching mask.Consequently, a drain electrode 21 and a source electrode 22 of the TFT20, an active semiconductor layer 28, a storage capacitor electrode 19(not shown in the figure), a drain bus line 14 (not shown in thefigure), a drain bus line terminal (not shown in the figure) and an a-Silayer 75 are formed. The channel protective film 23 functions as anetching stopper upon etching, and the a-Si layer 76 as an underlayerthereof is not etched but remains. The source electrode 22 iselectrically connected to an ITO layer 52 in the transmission area to bea transparent electrode 16 through the high melting point metal layer74. According to the aforementioned operations, a channel protectivefilm type TFT 20 is formed, and simultaneously a light shielding portion65 having the a-Si layer 73, the ITO layer 52 and the high melting pointmetal layer 74 accumulated is formed.

As shown in FIG. 20B, an SiN film is formed by the plasma CVD process onthe whole surface of the substrate to form a protective film 32. Aresist is then coated on the whole surface of the protective film 32 andpatterned by using a fifth photomask to form a resist pattern having apredetermined shape. The protective film 32 (and the insulating film 30)is subjected to dry etching using a mixed gas of a fluorine series gasand an O₂ gas by using the resist pattern as an etching mask.Consequently, a contact hole 26 on the source electrode 22, a contacthole (not shown in the figure) on the storage capacitor electrode 19 anda contact hole (not shown in the figure) on the gate bus line terminaland the drain bus line terminal are formed. Simultaneously, theprotective film 32 on the electroconductive film 54 in the transmissionarea is removed to form an opening 27.

A positive light-sensitive novolak resin, for example, is coated on thewhole surface of the substrate by using a spin coater or a slit coaterto form a light-sensitive resin layer having a thickness, for example,of about from 0.5 to 4 μm. Subsequently, the substrate is subjected to aheat treatment at a temperature of 160° C. or lower. The light-sensitiveresin layer is then exposed by using a sixth photomask and is developedby using an alkali developer solution, such as TMAH, so as to form an OClayer having a predetermined shape. The OC layer is formed on at least aportion of the area to be the reflection area. In the exposing step forpatterning, since the light shielding portion 65 is formed as anunderlayer (i.e., on the side of the glass substrate 10) of thelight-sensitive resin layer, light reflected on the exposing stage ofthe exposing apparatus is substantially not incident on thelight-sensitive resin layer in the reflection area.

The OC layer is then annealed at a temperature of from 100 to 180° C.for from 0.2 to 60 minutes by using a clean oven or a hot plate. Thesurface of the OC layer is then irradiated with UV light having awavelength of from 200 to 470 nm at an energy density of from 10 to 550mJ/cm² for from 5 to 300 seconds. Subsequently, depending on necessity,the glass substrate 10 is exposed from the back surface side thereof.The OC layer is then annealed by using a clean oven or the like at atemperature of from 180 to 230° C. for about 1 hour. Consequently, awrinkled resin layer 34 having wrinkled unevenness on the surfacethereof is formed in the reflection area (see FIG. 18). As described inthe foregoing, in this embodiment, light reflected by the exposing stageof the exposing apparatus is substantially not incident on thelight-sensitive resin layer in the reflection area, and therefore, awrinkled resin layer 34 having uniform wrinkled unevenness can beobtained through the subsequent UV light irradiation and heat treatment.

A Ti layer (or a Ti alloy layer) 17 a and an Al layer (or an Al alloylayer) 17 b are formed by sputtering on the whole surface of thewrinkled resin layer 34. A resist is then coated on the whole surface ofthe Al layer 17 b and patterned by using a seventh photomask to form aresist pattern having a predetermined shape. Subsequently, dry etchingusing a chlorine series gas is effected by using the resist pattern asan etching mask. Consequently, a reflection electrode 17 is formed inthe reflection area including the wrinkled resin layer 34. The surfaceof the reflection electrode 17 on the wrinkled resin layer 34 has awrinkled uneven surface following the surface of the wrinkled resinlayer 34. The reflection electrode 17 is electrically connected to thesource electrode 22 through the contact hole 26, and is electricallyconnected to the storage capacitor electrode 19 through a contact holenot shown in the figure. By the etching operation, the high meltingpoint metal layer 74 as an upper layer of the electroconductive film 54exposed through the opening 27 is removed, and the ITO layer 52 as alower layer remains, so as to form a transparent electrode 16.Thereafter, the substrate is subjected to a heat treatment at atemperature of from 150 to 230° C., preferably 200° C. According to theaforementioned process steps, the TFT substrate 2 shown in FIG. 18 iscompleted.

According to this embodiment, in the step of patterning the positivelight-sensitive resin layer for forming the wrinkled resin layer 34 inthe reflection area, light reflected from the exposing stage is shieldedby the light shielding portion 65 and the like, and thus the light issubstantially not incident on the light-sensitive resin layer in thereflection area, as similar to the first to seventh embodiments.Therefore, a heat treatment by applying energy to the surface thereof inthe subsequent step provides such a wrinkled resin layer 34 that hassubstantially uniform wrinkled unevenness formed thereon. Consequently,the reflection electrode 17 formed on the wrinkled resin layer 34 alsohas substantially uniform wrinkled unevenness to obtain a desiredinclined plane distribution with good controllability. According to thisembodiment, therefore, excellent reflection uniformity and stablereflectivity can be obtained to realize a transreflective liquid crystaldisplay device having good reflection display characteristics.

Furthermore, since the light shielding portion 65 is patterned by usingthe same photomask (the third photomask) as the transparent electrode16, as similar to the fifth to seventh embodiments. The high meltingpoint metal layer 74 on the transparent electrode 16 is removed throughthe etching step for forming the reflection electrode 17 after exposingthrough the opening 27 formed simultaneously with the contact hole 26.In this embodiment, therefore, the light shielding portion 65 is formedby using no additional photomask, and thus no process step is added tothe manufacturing method of the TFT substrate 2.

Ninth Embodiment

A liquid crystal display substrate according to a ninth embodiment ofthe invention and a manufacturing method thereof will be described withreference to FIGS. 21 to 23B. FIG. 21 is a cross sectional view showinga constitution of a TFT substrate 2 according to this embodiment. InFIG. 21, the area having a TFT 20 of a pixel formed therein is shown onthe left side, a transmission area of the pixel is shown at the center,and a reflection area of the adjacent pixel is shown on the right side,as similar to FIGS. 10 to 20B. As shown in FIG. 21, the TFT substrate 2of this embodiment has, on an insulating film 30 in the transmissionarea, an a-Si layer 75, which is formed with the same material with anactive semiconductor layer 28 of the TFT 20 integrally therewith. An SiNfilm 77 formed with the same material as a channel protective film 23 ofthe TFT 20 is formed on the a-Si layer 75. A transparent electrode 16 isformed on the SiN film 77. In the reflection area, a light shieldingportion 66 is formed on the insulating film 30 but as an underlayer of aprotective film 32. The light shielding portion 66 has such aconstitution that an a-Si layer 73 formed with the same material as theactive semiconductor layer 28, an SiN film 177 formed with the samematerial as the channel protective film 23, an ITO layer 52 formed withthe same material as the transparent electrode 16 and a high meltingpoint metal layer 74 are accumulated in this order. The layersconstituting the light shielding portion 66 are patterned into the sameshape. In this embodiment, while the a-Si layer 75 and the SiN film 77are formed as underlayers of the transparent electrode 16 in thetransmission area, the thickness of the active semiconductor layer 28 ofthe channel protective film type TFT 20 and the thickness of the a-Silayer 75 are about from 30 to 50 nm, and SiN film 77 has good lighttransmission, and thus the light transmittance in the transmission areais substantially not decreased.

A manufacturing method of the liquid crystal display substrate accordingto this embodiment will be described. FIGS. 22A to 23B are crosssectional views showing the manufacturing method of the TFT substrate 2according to this embodiment. As shown in FIG. 22A, an Al layer (or anAl alloy layer) 55 and a high melting point metal layer (an Mo layer) 56are formed in this order by sputtering directly on a glass substrate 10or after forming a protective film, such as SiO_(x), thereon dependingon necessity. Consequently, an electroconductive film containing the Allayer 55 and the high melting point metal layer 56 is formed. Additionalexamples of the high melting point metal include Cr, Ti, Ta, W andalloys thereof. A resist is then coated on the whole surface of theelectroconductive film and patterned by using a first photomask to forma resist pattern having a predetermined shape. Subsequently, dry etchingusing, for example a chlorine series gas is effected by using the resistpattern as an etching mask. Consequently, a gate bus line 12, a storagecapacitor bus line 18 (not shown in the figure) and a gate bus lineterminal (not shown in the figure) are formed.

As shown in FIG. 22B, an SiN film is formed by the plasma CVD process onthe gate bus line 12, the storage capacitor bus line 18 and the gate busline terminal on the whole surface of the substrate to form aninsulating film 30. An a-Si layer 76 is then formed by the plasma CVDprocess on the while surface of the insulating layer 30. Subsequently,an SiN film is formed by the plasma CVD process on the whole surface ofthe a-Si layer 76. An ITO layer 52 and a high melting point metal layer74 are formed by sputtering on the whole surface of the SiN film. Aresist is then coated on the whole surface of the high melting pointmetal layer 74 and patterned by using a second photomask to form aresist pattern having a predetermined shape. Subsequently, by using theresist pattern as an etching mask, the high melting point metal layer 74and the ITO layer 52 are subjected to wet etching by using, for example,a mixed reagent of acetic acid, nitric acid and phosphoric acid, and wetetching using, for example, a reagent, such as oxalic acid.Consequently, an electroconductive film 54 is formed in the transmissionarea, and an electroconductive film to be an upper layer of a lightshielding portion 66′ is formed on at least a portion of the reflectionarea.

A resist is then coated on the whole surface of the substrate. The glasssubstrate 10 is exposed from the back surface side thereof by using thegate bus line 12 as a mask. Subsequently, the glass substrate 10 isexposed from the front surface side by using a third photomask. Theresist layer is then developed, and the resist layer in the exposed areais removed by dissolution. Consequently, a resist pattern is formed in aself aligning manner only on the area for forming the channel protectivefilm on the gate bus line 12. The SiN film is then subjected to dryetching using a fluorine series gas by using the resist pattern, theelectroconductive film 54 in the transmission area and theelectroconductive film in the reflection area as an etching mask.Consequently, a channel protective film 23, an SiN film 77 as anunderlayer of the electroconductive film 54, and an SiN film 77 as anunderlayer of the light shielding portion 66′ are formed.

As shown in FIG. 23A, immediately after cleaning the surface of the a-Silayer 76 by using diluted hydrofluoric acid, an n⁺a-Si layer is formedby the plasma CVD process on the whole surface of the substrate. A highmelting point metal layer (such as a Ti layer or a Ti alloy layer) 57,an Al layer (or an Al alloy layer) 58 and a high melting point metallayer 59 are formed by sputtering in this order to form anelectroconductive film.

A resist is then coated on the whole surface of the electroconductivefilm and patterned by using a fourth photomask to form a resist patternhaving a predetermined shape. The electroconductive film, the n⁺a-Silayer and the a-Si layer 76 are subjected to dry etching using achlorine series gas by using the resist pattern as an etching mask.Consequently, a drain electrode 21 and a source electrode 22 of the TFT20, an active semiconductor layer 28, a storage capacitor electrode 19(not shown in the figure), a drain bus line 14 (not shown in thefigure), a drain bus line terminal (not shown in the figure) and a-Silayers 73 and 75 are formed. The source electrode 22 is electricallyconnected to the ITO layer 52 in the transmission area to be atransparent electrode 16 through the high melting point metal layer 74.According to the aforementioned operations, a channel protective filmtype TFT 20 is formed, and simultaneously a light shielding portion 66having the a-Si layer 73, the SiN film 77, the ITO layer 52 and the highmelting point metal layer 74 accumulated is formed.

As shown in FIG. 23B, an SiN film is formed by the plasma CVD process onthe whole surface of the substrate to form a protective film 32. Aresist is then coated on the whole surface of the protective film 32 andpatterned by using a fifth photomask to form a resist pattern having apredetermined shape. The protective film 32 (and the insulating film 30)is subjected to dry etching using a mixed gas of a fluorine series gasand an O₂ gas by using the resist pattern as an etching mask.Consequently, a contact hole 26 on the source electrode 22, a contacthole (not shown in the figure) on the storage capacitor electrode 19 anda contact hole (not shown in the figure) on the gate bus line terminaland the drain bus line terminal are formed. Simultaneously, theprotective film 32 on the electroconductive film 54 in the transmissionarea is removed to form an opening 27.

A positive light-sensitive novolak resin, for example, is coated on thewhole surface of the substrate by using a spin coater or a slit coaterto form a light-sensitive resin layer having a thickness, for example,of about from 0.5 to 4 μm. Subsequently, the substrate is subjected to aheat treatment at a temperature of 160° C. or lower. The light-sensitiveresin layer is then exposed by using a sixth photomask and is developedby using an alkali developer solution, such as TMAH, so as to form an OClayer having a predetermined shape. The OC layer is formed on at least aportion of the area to be the reflection area. In the exposing step forpatterning, since the light shielding portion 66 is formed as anunderlayer (i.e., on the side of the glass substrate 10) of thelight-sensitive resin layer, light reflected on the exposing stage ofthe exposing apparatus is substantially not incident on thelight-sensitive resin layer in the reflection area.

The OC layer is then annealed at a temperature of from 100 to 180° C.for from 0.2 to 60 minutes by using a clean oven or a hot plate. Thesurface of the OC layer is then irradiated with UV light having awavelength of from 200 to 470 nm at an energy density of from 10 to 550mJ/cm² for from 5 to 300 seconds. Subsequently, depending on necessity,the glass substrate 10 is exposed from the back surface side thereof.The OC layer is then annealed by using a clean oven or the like at atemperature of from 180 to 230° C. for about 1 hour. Consequently, awrinkled resin layer 34 having wrinkled unevenness on the surfacethereof is formed in the reflection area (see FIG. 21). As described inthe foregoing, in this embodiment, light reflected by the exposing stageof the exposing apparatus is substantially not incident on thelight-sensitive resin layer in the reflection area, and therefore, awrinkled resin layer 34 having uniform wrinkled unevenness can beobtained through the subsequent UV light irradiation and heat treatment.

A Ti layer (or a Ti alloy layer) 17 a and an Al layer (or an Al alloylayer) 17 b are formed by sputtering on the whole surface of thewrinkled resin layer 34. A resist is then coated on the whole surface ofthe Al layer 17 b and patterned by using a seventh photomask to form aresist pattern having a predetermined shape. Subsequently, dry etchingusing a chlorine series gas is effected by using the resist pattern asan etching mask. Consequently, a reflection electrode 17 is formed inthe reflection area including the wrinkled resin layer 34. The surfaceof the reflection electrode 17 on the wrinkled resin layer 34 has awrinkled uneven surface following the surface of the wrinkled resinlayer 34. The reflection electrode 17 is electrically connected to thesource electrode 22 through the contact hole 26, and is electricallyconnected to the storage capacitor electrode 19 through a contact holenot shown in the figure. By the etching operation, the high meltingpoint metal layer 74 as an upper layer of the electroconductive film 54exposed through the opening 27 is removed, and the ITO layer 52 as alower layer remains, so as to form a transparent electrode 16.Thereafter, the substrate is subjected to a heat treatment at atemperature of from 150 to 230° C., preferably 200° C. According to theaforementioned process steps, the TFT substrate 2 shown in FIG. 21 iscompleted.

According to this embodiment, in the step of patterning the positivelight-sensitive resin layer for forming the wrinkled resin layer 34 inthe reflection area, light reflected from the exposing stage is shieldedby the light shielding portion 66 and the like, and thus the light issubstantially not incident on the light-sensitive resin layer in thereflection area, as similar to the first to eighth embodiments.Therefore, a heat treatment by applying energy to the surface thereof inthe subsequent step provides such a wrinkled resin layer 34 that hassubstantially uniform wrinkled unevenness formed thereon. Consequently,the reflection electrode 17 formed on the wrinkled resin layer 34 alsohas substantially uniform wrinkled unevenness to obtain a desiredinclined plane distribution with good controllability. According to thisembodiment, therefore, excellent reflection uniformity and stablereflectivity can be obtained to realize a transreflective liquid crystaldisplay device having good reflection display characteristics.

Furthermore, since the light shielding portion 66 is patterned by usingthe same photomask (the second photomask) as the transparent electrode16, as similar to the fifth to eighth embodiments. The high meltingpoint metal layer 74 on the transparent electrode 16 is removed throughthe etching step for forming the reflection electrode 17 after exposingthrough the opening 27 formed simultaneously with the contact hole 26.In this embodiment, therefore, the light shielding portion 66 is formedby using no additional photomask, and thus no process step is added tothe manufacturing method of the TFT substrate 2.

Tenth Embodiment

A liquid crystal display substrate according to a tenth embodiment ofthe invention and a manufacturing method thereof will be described withreference to FIGS. 24 to 26B. FIG. 24 is a cross sectional view showinga constitution of a TFT substrate 2 according to this embodiment. InFIG. 24, the area having a TFT 20 of a pixel formed therein is shown onthe left side, a transmission area of the pixel is shown at the center,and a reflection area of the adjacent pixel is shown on the right side,as similar to FIGS. 10 to 23B. As shown in FIG. 24, the TFT substrate 2of this embodiment has a transparent electrode 16 on an insulating film30 in the transmission area. In the reflection area, a light shieldingportion 67 is formed on the insulating film 30 but as an under layer ofa protective film 32. The light shielding portion 67 has such aconstitution that an ITO layer 52 formed with the same material as thetransparent electrode 16 and a high melting point metal layer 74 areaccumulated in this order. The layers constituting the light shieldingportion 67 are patterned into the same shape.

A manufacturing method of the liquid crystal display substrate accordingto this embodiment will be described. FIGS. 25A to 26B are crosssectional views showing the manufacturing method of the TFT substrate 2according to this embodiment. As shown in FIG. 25A, an Al layer (or anAl alloy layer) 55 and a high melting point metal layer (an Mo layer) 56are formed in this order by sputtering directly on a glass substrate 10or after forming a protective film, such as SiO_(x), thereon dependingon necessity. Consequently, an electroconductive film containing the Allayer 55 and the high melting point metal layer 56 is formed. A resistis then coated on the whole surface of the electroconductive film andpatterned by using a first photomask to form a resist pattern having apredetermined shape. Subsequently, dry etching using, for example achlorine series gas is effected by using the resist pattern as anetching mask. Consequently, a gate bus line 12, a storage capacitor busline 18 (not shown in the figure) and a gate bus line terminal (notshown in the figure) are formed.

As shown in FIG. 25B, an SiN film is formed by the plasma CVD process onthe gate bus line 12, the storage capacitor bus line 18 and the gate busline terminal on the whole surface of the substrate to form aninsulating film 30. An a-Si layer is then formed by the plasma CVDprocess on the while surface of the insulating layer 30. Subsequently,an SiN film is formed by the plasma CVD process on the whole surface ofthe a-Si layer. A resist is then coated by spin coating or the like onthe whole surface of the SiN film to form a resist layer. The glasssubstrate 10 is then exposed from the back surface side thereof by usingthe gate bus line 12 as a mask. Subsequently, the glass substrate 10 isexposed from the front surface side thereof by using a second photomask.The resist layer is then developed, and the resist layer in the exposedarea is removed by dissolution. Consequently, a resist pattern is formedin a self aligning manner only on the area for forming the channelprotective film on the gate bus line 12. Dry etching using a fluorineseries gas is then effected by using the resist pattern as an etchingmask to form a channel protective film 23.

Immediately after cleaning the surface of the a-Si layer by usingdiluted hydrofluoric acid, an n⁺a-Si layer is formed by the plasma CVDprocess on the whole surface of the substrate. A high melting pointmetal layer (such as a Ti layer or a Ti alloy layer) 57, an Al layer (oran Al alloy layer) 58 and a high melting point metal layer 59 are thenformed by sputtering in this order to form an electroconductive film.

A resist is then coated on the whole surface of the electroconductivefilm and patterned by using a third photomask to form a resist patternhaving a predetermined shape. The electroconductive film, the n⁺a-Silayer and the a-Si layer are subjected to dry etching using a chlorineseries gas by using the resist pattern as an etching mask. Consequently,a drain electrode 21 and a source electrode 22 of the TFT 20, an activesemiconductor layer 28, a storage capacitor electrode 19 (not shown inthe figure), a drain bus line 14 (not shown in the figure) and a drainbus line terminal (not shown in the figure) are formed. According to theaforementioned operations, a channel protective film type TFT 20 isformed.

As shown in FIG. 26A, an ITO layer 52 and a high melting point metallayer 74 are formed by sputtering on the drain electrode 21 and thesource electrode 22 on the whole surface of the substrate. A resist isthen coated on the whole surface of the high melting point metal layer74 and patterned by using a fourth photomask to form a resist patternhaving a predetermined shape. Subsequently, by using the resist patternas an etching mask, the high melting point metal layer 74 and the ITOlayer 52 are subjected to wet etching by using, for example, a mixedreagent of acetic acid, nitric acid and phosphoric acid, and wet etchingusing, for example, a reagent, such as oxalic acid. Consequently, anelectroconductive film 54 is formed in the transmission area, and alight shielding portion 67 is formed on at least a portion of thereflection area.

As shown in FIG. 26B, an SiN film is formed by the plasma CVD process onthe whole surface of the substrate to form a protective film 32. Aresist is coated on the whole surface of the protective film 32 andpatterned by using a fifth photomask to form a resist pattern having apredetermined shape. The protective film 32 (and the insulating film 30)is subjected to dry etching using a mixed gas of a fluorine series gasand an O₂ gas by using the resist pattern as an etching mask.Consequently, a contact hole 26 on the source electrode 22, a contacthole (not shown in the figure) on the storage capacitor electrode 19 anda contact hole (not shown in the figure) on the gate bus line terminaland the drain bus line terminal are formed. Simultaneously, theprotective film 32 on the electroconductive film 54 in the transmissionarea is removed to form an opening 27.

A positive light-sensitive novolak resin, for example, is coated on thewhole surface of the substrate by using a spin coater or a slit coaterto form a light-sensitive resin layer having a thickness, for example,of about from 0.5 to 4 μm. Subsequently, the substrate is subjected to aheat treatment at a temperature of 160° C. or lower. The light-sensitiveresin layer is then exposed by using a sixth photomask and is developedby using an alkali developer solution, such as TMAH, so as to form an OClayer having a predetermined shape. The OC layer is formed on at least aportion of the area to be the reflection area. In the exposing step forpatterning, since the light shielding portion 67 is formed as anunderlayer (i.e., on the side of the glass substrate 10) of thelight-sensitive resin layer, light reflected on the exposing stage ofthe exposing apparatus is substantially not incident on thelight-sensitive resin layer in the reflection area.

The OC layer is then annealed at a temperature of from 100 to 180° C.for from 0.2 to 60 minutes by using a clean oven or a hot plate. Thesurface of the OC layer is then irradiated with UV light having awavelength of from 200 to 470 nm at an energy density of from 10 to 550mJ/cm² for from 5 to 300 seconds. Subsequently, depending on necessity,the glass substrate 10 is exposed from the back surface side thereof.The OC layer is then annealed by using a clean oven or the like at atemperature of from 180 to 230° C. for about 1 hour. Consequently, awrinkled resin layer 34 having wrinkled unevenness on the surfacethereof is formed in the reflection area (see FIG. 24). As described inthe foregoing, in this embodiment, light reflected by the exposing stageof the exposing apparatus is substantially not incident on thelight-sensitive resin in the reflection area, and therefore, a wrinkledresin layer 34 having uniform wrinkled unevenness can be obtainedthrough the subsequent UV light irradiation and heat treatment.

A Ti layer (or a Ti alloy layer) 17 a and an Al layer (or an Al alloylayer) 17 b are formed by sputtering on the whole surface of thewrinkled resin layer 34. A resist is then coated on the whole surface ofthe Al layer 17 b and patterned by using a seventh photomask to form aresist pattern having a predetermined shape. Subsequently, dry etchingusing a chlorine series gas is effected by using the resist pattern asan etching mask. Consequently, a reflection electrode 17 is formed inthe reflection area including the wrinkled resin layer 34. The surfaceof the reflection electrode 17 on the wrinkled resin layer 34 has awrinkled uneven surface following the surface of the wrinkled resinlayer 34. The reflection electrode 17 is electrically connected to thesource electrode 22 through the contact hole 26, and is electricallyconnected to the storage capacitor electrode 19 through a contact holenot shown in the figure. The reflection electrode 17 is alsoelectrically connected to the transparent electrode 16 through a portionof the opening 27. By the etching operation, the high melting pointmetal layer 74 as an upper layer of the electroconductive film 54exposed through the opening 27 is removed, and the ITO layer 52 as alower layer remains, so as to form the transparent electrode 16.Thereafter, the substrate is subjected to a heat treatment at atemperature of from 150 to 230° C., preferably 200° C. According to theaforementioned process steps, the TFT substrate 2 shown in FIG. 24 iscompleted.

According to this embodiment, in the step of patterning the positivelight-sensitive resin layer for forming the wrinkled resin layer 34 inthe reflection area, light reflected from the exposing stage is shieldedby the light shielding portion 67 and the like, and thus the light issubstantially not incident on the light-sensitive resin layer in thereflection area, as similar to the first to ninth embodiments.Therefore, a heat treatment by applying energy to the surface thereof inthe subsequent step provides such a wrinkled resin layer 34 that hassubstantially uniform wrinkled unevenness formed thereon. Consequently,the reflection electrode 17 formed on the wrinkled resin layer 34 alsohas substantially uniform wrinkled unevenness to obtain a desiredinclined plane distribution with good controllability. According to thisembodiment, therefore, excellent reflection uniformity and stablereflectivity can be obtained to realize a transreflective liquid crystaldisplay device having good reflection display characteristics.

Furthermore, since the light shielding portion 67 is patterned by usingthe same photomask (the fourth photomask) as the transparent electrode16, as similar to the fifth to ninth embodiments. The high melting pointmetal layer 74 on the transparent electrode 16 is removed through theetching step for forming the reflection electrode 17 after exposingthrough the opening 27 formed simultaneously with the contact hole 26.In this embodiment, therefore, the light shielding portion 67 is formedby using no additional photomask, and thus no process step is added tothe manufacturing method of the TFT substrate 2.

The invention encompasses various modifications in addition to theaforementioned embodiments.

For example, while a transreflective liquid crystal display device isexemplified in the aforementioned embodiments, the invention is notlimited thereto and can be applied to a reflection liquid crystaldisplay device.

1. A liquid crystal display substrate comprising: a plurality of pixel areas each having at least a portion thereof a reflection area reflecting light incident from a front surface side of the substrate; a wrinkled resin layer formed with a positive light-sensitive resin in the reflection area, the wrinkled resin layer having at least a portion thereof a wrinkled surface; a reflection electrode formed with a light reflection material on the wrinkled resin layer, the reflection electrode having a wrinkled surface following the surface of the wrinkled resin layer; a light shielding portion formed as an underlayer of the wrinkled resin layer, the light shielding portion shielding light incident from a back surface side of the substrate; and a thin film transistor formed in each of the pixel areas, wherein at least a portion of the light shielding portion is formed in a same layer with the same material as a drain electrode and a source electrode of the thin film transistor.
 2. A liquid crystal display substrate as claimed in claim 1, wherein the light shielding portion is electrically separated from the drain electrode and the source electrode.
 3. A liquid crystal display substrate comprising: a plurality of pixel areas each having at least a portion thereof a reflection area reflecting light incident from a front surface side of the substrate; a wrinkled resin layer formed with a positive light-sensitive resin in the reflection area, the wrinkled resin layer having at least a portion thereof a wrinkled surface; a reflection electrode formed with a light reflection material on the wrinkled resin layer, the reflection electrode having a wrinkled surface following the surface of the wrinkled resin layer; a light shielding portion formed as an underlayer of the wrinkled resin layer, the light shielding portion shielding light incident from a back surface side of the substrate; and a thin film transistor formed in each of the pixel areas, wherein at least a portion of the light shielding portion is formed in a same layer with the same material as an active semiconductor layer of the thin film transistor.
 4. A liquid crystal display substrate as claimed in claim 3, wherein the light shielding portion is electrically separated from the active semiconductor layer.
 5. A method of manufacturing a liquid crystal display substrate having a reflection area reflecting light incident from a front surface side of a substrate, and a transparent area transmitting light incident from a back surface side of the substrate, in each of the pixel areas, the method comprising the steps of: forming a first electroconductive film having light transmittance and a second electroconductive film having light shielding capability in this order on the substrate; forming a light shielding portion in the reflection area and an electroconductive layer having a predetermined shape in the transmission area by patterning the first and second electroconductive films; forming an insulating film on the light shielding portion and the electroconductive layer; exposing the electroconductive layer by removing the insulating film in the transmission area; forming a transparent electrode by removing the second electroconductive film of the exposed electroconductive layer; forming a resin layer having a predetermined shape on the insulating film in the reflection area; forming a wrinkled resin layer having wrinkled unevenness on at least a portion of a surface thereof by curing and heat treating a surface of the resin layer; and forming a reflection electrode on the wrinkled resin layer.
 6. A method of manufacturing a liquid crystal display substrate as claimed in claim 5, wherein a gate electrode of a thin film transistor is formed simultaneously with forming the light shielding portion and the electroconductive layer.
 7. A method of manufacturing a liquid crystal display substrate as claimed in claim 5, wherein the step of forming a wrinkled resin layer comprises a step of exposing the resin layer from a back surface side of the substrate before heat treatment so as to prevent the wrinkled unevenness from being formed on the resin layer in an area having no light shielding portion formed. 